114998994 Physics Spm Paper 2 Tips 89 Modification and 11 Decision Making Question and Answer

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CHAPTER 1

1. Suitable ruler to use in laboratory

Suggestion Explanation Smallest size scale 0.1 cm More accurate

High accuracy Less error in measurement High consistency Low relative deviations Plastic material Avoid parallax error Thin thickness Avoid parallax error CHAPTER 2

2. Explain the suitability feature of arm exercise equipment.

Suggestion Explanation

Spring made of steel Can withstand higher force Two // more spring arrange in parallel The spring system is stiffer Spring with ticker wire Wire will not easily break

Smaller diameter coil of spring The smaller the diameter coil less elastic the spring, so the arm exercise would not so hard Choose large force constant spring Will make strong spring, the spring will stiffer and

not broken easily

3. Suggest the suitable cloth , equipment and techniques to improve high jumper athlete and

their safety .

4. Explain the characteristic of spring to make baby’s cradle.

Choose large force constant spring Will make strong spring, the spring will stiffer and not broken easily.

Choose large diameter of wire The larger diameter the stiffer the spring is.

Large diameter coil of spring The larger the diameter coil more elastic the spring is

The spring is made of steel or alloy Steel and alloy is stiffer than iron The arrangement of spring is two or

more line in parallel

The spring is stiffer

5. Explain the most suitable design of spring for shock absorber for motorcycles.

Small diameter of spring coil Enough space for the spring

Choose large diameter of wire The larger the diameter the stiffer the spring Force constant is more than 1000N Can support motorcyclist and passenger up to

100kg

Higher spring constant Small compression of the spring

Small natural frequency To reduce bumping, comfortable for user

6. Explain the simple characteristic of the rocket than can travel with greater acceleration.

Suggestions Explanations

Choose metal with high strength and

hardness Even under pressure the shape will not change easily Frame of rocket is made of low density Lighter, can increase acceleration

suggestion Explanation

Use tight and light suit Less air fraction

Use spikes shoes Better grip support while running and prevent slippery

Use thicker mattress Increase time impact , reduce impulsive force . prevent back injury

The athlete have to sprint before jump Can increase kinetic energy Athlete have to bend the body during

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metal

Multistage rocket invented Each stage has burning fuel, pump and combustion chamber. It will slip off when fuel of each chamber completely burn. When the mass decreases, the acceleration increase

Rocket need to carry a tank of oxygen To enable the combustion of fuel in space

Silver color rocket Reflect light efficiently so the temperature of the rocket will not rise

Cover the body of rocket with heat insulator

Friction between air and body will increase heat. The insulator will reduce heat conductivity Aerodynamic shape Reduce air friction, move faster

7. Suggest and explain the build of water bottle rocket in school competition to move higher altitude and has longer time on the air.

The body of rocket must be tough Do not break easily in high pressure and when landing

Smaller mass Rocket will accelerate faster The shape is streamline/aerodynamic Reduce air resistance

Nose cone or bullet shape on top of

body To improve the aerodynamic of rocket

45 angle of launching The rocket can travel maximum distance The volume of water is half or 1/3 from

the whole volume To increase momentum and impulsive force Attach 3 or 4 fins at the tail of rocket

space equally

Rocket will move smooth and stable

Attach parachute will make the rocket floating and has longer time on the air before landing//decrease the speed of falling due to air resistance

8. Give suggestion to improve the design of jet engine so that it can be use for larger airplane at the higher speed.

Increase more fuel injectors More fuel to be burnt to produce greater force Increase the size of the combustion

chamber

More space for fuel to burnt

Decrease the diameter of the nozzle Exhaust gas ejected at higher velocity Increase the speed of blade/use bigger

blade

Increase the air intake Blade and engine made of strong

materials Can withstand strong pressure and won’t break easily 9. Base on the physic principle, suggest the design of roller skate track so it can be use to

oscillate skate continuously.

Semi circular curve shape Exchange between kinetic energy and gravitational potential easily

Smooth surface Reduce frictional force/easy to slide The slope slightly increase and

decrease

Easy to oscillates cause by changing of energy Use strong material such concrete of

foundation of the track Withstand high impact such as high force of jumping and landing Soft layer at the surface Reduce impulsive force when landing, low risk if

accident

10. Explain the most suitable design of motorcycle that can move fast, safe and save time in racing.

Lower seat height Lower center of gravity or more stable or safer to turn.

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acts on the tires or more friction when breaks. Less thread pattern To decrease friction of tires to the road, can move

fast

Smaller mass Lighter, can move faster or low inertia

With ABS Motorcycle does not stop immediately or can be controlled if direction changes or does not move sideways or more friction with ABS

11. Suggest and explain how to make suitable beach motorcycle which able to move on the sand smoothly and comfortable.

Deep thread patter // more definitive

pattern Better grip on sand, able to move smoothly onsand Large tire (big surface contact with

ground)

Reduce total pressure of car, increase stability and the car would not get stuck in the sand

Soft seat and water resistance Comfortable for cycles and would not get wet easily

Excellent resistance to rusting Everlasting. Would not rust easily Attach shock absorber with higher

spring constant and small natural frequency.

Reduce bumping, comfortable to cycle with Low density body Lighter, would not stuck in sand

12. Suggest the suitable cloth and the best techniques to catch ball to prevent injury for goalkeeper.

Suggestion Explanations

Wear glove Reduce painful of the player’s hands when touching the ball with big impulsive force.

Use soft material for glove Lengthen the time impact, reduce impulsive force. Wear cloth which is made from material

with moderate specific heat capacity

The cloth can absorb more heat when the player is sweating to maintain the temperature of player. Base of shoes has stud Player give great pressure to make stud sink into

ground and give stronger support without slipping. When catching the ball, the goal keeper

should move his hand backwards

This action lengthen the time impact between ball and hand, so it reduce the impulsive force.

The ball should have enough air pressure inside

Shorter the time impact between foot and ball, so impulsive force increase then the ball will has high speed and travel far away.

13. Using physics concept, suggest and explain suitable athlete’s attires, running, jumping, landing techniques and other aspects to help the long jumper can jump further.

Use tight and light suit Less air friction

Use spike shoes Better grip support while running and prevent slippery

The athlete have to sprint before jump Can increase the kinetic energy//momentum The athlete have to push the body

infront while jumping

Increase the elastic potential energy//able to increase longer distance of jumping

Athlete have to bent the body during fall

Increase the time impact, reduce impulsive force, less injured

14. Safety feature in car

Characteristic Explanation

The bumper of car is prone to crash It will increase the time impact, the impulsive force will reduce

The sitting space of the passenger is

reinforced To protect the passenger

Use safety belt During collision, safety belt will hold the passengers from thrown infront due to inertia Use air bag Will inflate when accident occurs, the driver safe

from hitting steering

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prevent from skidding

Strong steel struts Give good protection from side on collision Tire with tread Can stays contact with road, prever slippery 15. Explain the suitable loaded lorry which can carry liquid, such as petrol

The load of lorry should be divided into many smaller tank

To reduce effect of inertia The load must be tied So it will no fall of from the lorry Far gap distances between tractor and

trailer

Prevent collision between tractor and trailer, easier when turning

Use more tire for lorry Pressure will be separate to all tires, able to carry more loads. Lower pressure better support and stability

Small belt behind lorry To discharge spark, safety reason to prevent from burning the petrol

Use antilock break system (ABS) The lorry can stop easily without skidding 16. Explain the design of and how kayak which can travel faster and safer.

Streamline /aerodynamic shape of body Reduce water resistance

Smooth surface body /coated with wax Reduce friction of body towards water

Low density material Lighter , easier to float, easy to carry and sail faster

Strong material body and peddle Everlasting , not easily broken

Wider peddle surface Greater force because more water are peddled up Wear safety jacket Passenger can float and safe if they fall into water. 17. Give suggestion to design a sail boat which can travel faster and smooth.

Streamline /aerodynamic shape of

board Reduce water and air resistance,can increase lifting Smooth surface board/coated with wax Reduce friction toward water

Low density material Lighter, easier to float and sail faster Strong material Withstand strong wind, not easily damage Wider sail Greater lifting force because more wind are

captured

18. Modified the ship that can carry more and heavier load, move faster and safe while travelling.

Strong material Can withstand great force Low density material Light weight

Has more than two stage,plimsoll line Safe to travel on the fresh and salt water

Big size Can place more goods

Aerodynamic/streamline shape Reduce water friction.

Waterproof sail Sail would not get e=wet easily.

19. Suggest how to increase the safety for motorbike racer to reduce injuries / accident

20. A

n earth-monitoring satellite falls into the earth’s atmosphere at a high velocity and reaches a high temperature. This is caused by the earth’s gravitational force and air resistance.Using the appropriate physics concepts, suggest and explain suitable designs or ways to protect the satellite and its equipment:

Use helmet To protect the head

Use helmet with hard outer casing and soft inner liner

Helmet reduce head injuries in a crash by

spreading the impact with hard outer casing and absorb energy with soft inner linear of styrofoam Use safety jacket To protect the from injuries , cut ,burn

Use gloves To protect the hand

Use padded leathers suit Will soften any impact and protect the skin from abrasion

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Suggestion Explanation Aerodynamic shape To reduce air resistance

Heat shield / material that is hard to burn

To protect the capsule High melting point //ceramic Do not melt

Landing in water // air bag Increase time of impact// Reduce impulsive force Light material / / small mass // low

density

-Reduce the inertia // -reduce the momentum // -reduce impuls

Paracute / /Retro rocket To reduce speed Hard material // stiff composite Not easy to bend

21. Explain how you would design the pile driving system.[the ram hammer is lifted to a height by the crane and allowed to fall on the pile.

Modification Reason

Large hammer weight Large momentum when it hit the pile Ram hammer made from hard material

such as alloys

Not break easily/last longer

Hammer raised at higher position Inrease the gravitational potential energy Stronger End of the top of the concrete

pile

To avoid break at the top couse by the hammer Sharp End of the bottom of the

concrete pile To increase the pressure CHAPTER 3

22. Efficient brake system

Type of liquid: oil Uncompressible

Thickness of brake line :high To counter the high pressure from the liquid The ratio of cross sectional area for

wheel piston and master piston :high

To produce larger force on wheel piston The chosen of type of brake for front

rear wheel: Front wheel - disc Rear wheel - drum

Disc brake is more efficient than drum brake

23. Explain the design of hydrometer which can be use to determine a wide range of densities of liquid.

Small stem and long Increase sensitivity where the scale division are far apart so that small changes in density can be detected

Glass wall Do not erode and small adhesive force

Large diameter of bulb High up thrust / displaces more liquid / able to float easily

Scale can be made bigger or smaller than the density of water.[calibration]

- The hydrometer is floated in alcohol. The liquid level at the stem is marked (upper level) - Then, the hydrometer is floated

in higher density liquid like mercury and marked (lower level)

Ability to measure a wide range of densities of liquids.

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24. Describe the suitable design to build mobile tent for Sure Heboh event which will be construct at open space for a week. Using appropriate physics concept, suggests and explain.

Suggestion Explanation

Choose low density metal for frame Light weight and strong

Use hollow rod which can assemble easily Hollow rod is not heavy, but equally strong, easy to mobile anywhere, faster to build, can reduce the cost of construction and transport Water proof canvas If raining, would not getting wet

Anti rust rod Can withstand rain and long lasting Sharp end rod Small surface area, so higher pressure to

ground, yet the tent can be planted into ground firmly and stand still

25. Explain the necessary modification for the structure of dentist chair for children that are suitable and save for the adult.

Increase the cross-sectional area of big piston and decrease the cross-sectional area of small piston

To increase the output force acting on big piston / to lift havier adult / to increase force multiplier of system

The wall of pipe is made up of strong alloy to hold the fluid

To withstand the strong pressure that might cause cracking in the channel

Change the less control into electric touch

control To lift or lowered the chair to the desire weight more easily and safety The surface area of the seat enlarged To support the people with the large bodies Use non-corrosive oil in jack So that the wall of the pipe will not be controlled

and cause leakage

26. Explain the build and design of hot air ballon wich can fly higher altitude faster and suggest some safety aspect.

Large ballon Produce bigger buoyant / upthrust force, increase the volume of air displacement Many hot air burner Heat up the gas inside faster

Synthetic nylon ballon Air proof, light weight and strong material Gas temperature is high Reduce the density of air in ballon

Total of mass is low Ballon move upward faster

Rattan basket Longer the time impact, reduce the impulsive force to passanger when landing

Fly on early morning or late afternoon The temperature outside the ballon is cooler compare to the inside of ballon, so the ballon will rise higher

27. Explain the basic structure of small submarine that can be use for underwater exploration.

Strong material Does not break easily Aerodynamic shape Reduce water resistance

Thick wall Water pressure increase with depth High density materials Increase mass / can submerge easily Ballast tank To increase or reduce weight

Sonar transmitter and receiver To estimate and depth

28. Suggest the design of submarine which can submerge and float in the sea.

Ballast tank are partially filled with water The submarine will partially float Aerodynamic // streamline body To reduce water resistance

Use hard and stiff materials for body To overcome the pressure of water in the sea Attach periscope To view surrounding area when submarine float Use nuclear power sources to generate

power

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29. Explain the characteristic of material to be use for making the sole of jungle trekking shoes.

Rubber sole Good impact absorber

Low density Light weight

Many stud Give extra grip

Low expansion effect Not loose easily

Excellent ability of stretch Comfortable to feet, foot can move unstressed 30. Using physics concept, explain necessary deep sea diving suit and other accessory to carry.

Choose strong helmet with thick metal and

glass to cover head To withstand high pressure of water and protect the head Use thick glass in front of diver face Enable the diver to see surrounding and at the

same time able to withstand the pressureof water

Use water proof suit and able to withstand

pressure Due to depth, the pressure under water is very high Bring along gas containing mixture of

oxygen To provide oxygen to diver for breath

Use very heavy suit The diver enable to stand on the floor of ocean and able to fight buoyancy of water

31. Modified the passanger airplane to cargo airplane that needs to carry more laod, less use of fuel, effenciency and safety to travel.

Increase the size of the body To increase the space Increase the length of the wing To increase the upthrust

Increase the thickness of the body To stand higher pressure difference

Use a more powerful engine To overcome bigger inertia and do more work per unit time

Increase the number of tyres To support higher mass or pressure while landing

Protective bar between the cabin and the

pilot To prevent moving object to knock at the pilot while landing Pilot has ejected seat during emergency To save the pilot if plane crash happened 32. Design Vacuum Cleaner

Large fan driven Inrease the spped and amaunt of airflows Powerfull of lectric motor Inrease the spped and amaunt of airflows Narrower inlet opening Inrease the velocity/decrease air pressure Using a very large filter to block dust

particles while allowing air moleculs to pass through

To have a lots of surface area and many pores for air to flow through

Larger spaced for depositing and collecting

the dust particles Ensure that the air flows through the filter is not block by too many dust particles 33. Design paint sprayer

Large size of air vessel Compress more air/can exert large pressure Rubber material for the vessel More elastic/easier to squeeze

Narrow shape of the tube Air can move with high speed Fibre glass material for the rod Stronger and last longer

Size of nozzle is narrow at the end The paint can be sprayed evenly 34. Design hidraulic jack

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Suggestion Explanation Bigger crossectional area of slave piston(big

piston) Produced higher force

Small crossectional area of master piston(small piston)

Less forced is needed/produced bigger pressurre

Longer handle Less forced is needed to press small piston(master piston)

Low density of a body Lighter

Oil for liquid Non-compressable

Release valve between small and main reservoir(reset)

Liquid can flows into small reservoir easily when push the reset button.

35. Design hydrometer

Bulb with lead shot at the lower section To submerge the hydrometer and not overturn Cylinder with bigger diameter at the bottom not overturn/increase stability

Cylinder with smaller diameter at the upper section

A small reading scale can be incorporated/inrease the sensitivity Smaller scale inrease the sensitivity

Filled with air Inrease the beyoncy force

Glass wall Not corrode easily

CHAPTER 4

36. Most suitable design of thermometer to use in Antarctica

Use alcohol as liquid – in glass thermometer Freezing point of alcohol is -115o_{C .So , it will} not freeze at low temperature

Use thin wall of bulb So it will sensitive to the change of heat Use small diameter of capillary tube Alcohol can expand at high rate for the small

change in temperature

Use thick glass wall The loss of heat to surrounding is small Use round glass stem Can act as magnifying glass , so the alcohol

level can be seen clearer 37. Most suitable design of clinical thermometer

Use mercury Easy to read because it colour and opaque The scale range from 35o_{C to 42}o_C _{To measure human body heat}

Small diameter of capillary tube// extra fine

bore tube Mercury can expand at high rate for a small change in temperature Use thin glass wall of bulb Sensitive to change of temperature

Use round glass stem and wall Can act as ,magnifying glass. So, mercury can be seen clearly

38. Explain the design and the characteristics of the cooking pan

Base is made of a copper Copper has a lower heat capacity it become hot very quickly

High density of base Heavier base make the pot stable and not topple over easily

Body is made of aluminium Low specific heat capacity becomes hot very quickly but it low density make it overall weight of weight lighter

Handle is made of wood or plastic High specific heat capacity so the handle do not become hot . Safe

Choose low density material for handle Does not add much to the total weight of pot Transparent pot cover Able to cooker to see the food. Food cover will

trap the heat

39. Suggest and explian the design of water heater to boil a large quantity of water faster ,efficient and safely

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Suggestion Explanation Use tungsten High melting point,high heat energy

Coiled Longer wire,increase the resistance

High melting point Not easy to melt at high temperature Lower rate of rusting Does not get rust easily

Use thermostat When temperatures reach 100 Celsius, the water heater will automatically turn off

40. Determine the modification to be made for container,so the cut fruit will keep cool, remain fresh and easily seen by customers.

Use container with high specific heat

capacity Able to slow down the loss of heat from the container Place small ice packet below the bottom of

the cut friuts The cut fruits is chill and juicy, ice able to absorb a large amount of latent heat when melt

Add salt to the packet of ice Foreign matter will increase the freezing point of ice, so this will slow down the ice from melting

White wall colour of container Can avoid absorbtion of heat from the surrounding

The container has double wall Avoid heat from surrounding transferred easily to container. The inside container remains cool Transparent wall of container in front of

customer The customer can see and choose the cut fruitseasily 41. Investigate the most suitable liquid that can be use as coolant for car engine using physics

concept.

Low freezing point liquid Will not freeze easily during winter weather High boiling point liquid Do not easily boil when absorbing heat from

the engine

High specific heat capacity liquid Can transfer large contain of heat with a small rise in temperature. Able to cool up the engine Low ability to react with metal The metal part of the engine will not corrode

easily

42. Most suitable thermometer for laboratory to measure the temperature of ice and boiling point of water

Size of the bulb is small Does not need a lot of heat to heat up the mercury to expand

Use thin wall of bulb So it is sensitive to change of heat

Use mercury Freeezing point of the mercury is -39 degree celsius and boling point 357 degree celsius . Able to has a range from -10 to 110 degree Celsius. Mercury can expand a high rate for small change of temperature

Use thin wall capillary Able quick heat transfer from the surrounding to the mercury. So, the thermemeter is more sensitive

Has minimum size scale with small division

Making thermometer a sensitive instrument 43. Modified and explain the design of an efficient solar water-heating system on the roof.

Pipe embedded in plate must be long Longer pipe will has greater surface area which can absorb heat faster

Use metal pipe as pipe inside the plate Metal is good heat conductor , so heat will easily transmit to water

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Use insulator behind the absorber panel Insulator will prevent the heat loss Use black absorber panel Black is good heat absorber

Cover the top of the panel with glass Heat will trap inside due to green house effect Put the tank at higher level To give higher pressure

44. Explain the build of solar cooker oven that been use in science month competition at your school to boil 500ml water in short time.

Build the solar cooker with shiny// silver colour reflector inside

The light will reflect to the cooker and heat up the water

Use metal cooker Good conductor

Paint the outside part of the solar cooker and the cooker ( contain water ) with black colour

To absorb

Wrap the cooker with plastic or glass Avoid heat from release to sorrounding To trap heat, the temperataure will

increase

To absorb heat, the water boil faster

45. Suggest the design of heating system in the house and characteristics of heating agent. The house use central heating system with boiler, radiator and pipelines.

Use strong material Not easily break

Use metal pipe with good heat conductor Increase the rate of heat transfer

Increase length of cooling coil Can transfer the heat faster to surrounding Use greater boiling point liquid Liquid not easily change into vapour

Low rate of rusting material Long lasting, not easily rust

The bigger size of radiator fan Can blow and cool down larger area Pipe in coil structure is used Increase the time of floe and increase the

quantity of haet transferred.

46. Suggest the characteristic of material to build food container which can keep the food warm.

Food container should made of low

density material Lighter , the container able to be move from one place to another. Melting point of container should be

high

To prevent the container from melting up when hot food is store inside

Specific heat capacity should be high So the container will not get hot easily. Safe to touch and handle.

Thermal conductivity is low.i Good heat insulator , to ensure the heat not loss and the food remain hot.

Double wall To prevent hest loss.

47. Explain the characteristic and design of thermos flasks to maintain hot water.

Use hollow plastic stopper Able to trap air as air is poor heat

conductor.so,less heat loss through stopper. Vacuum space Prevent heat loss through conduction or

convection

Has double wall Has vacuum in between heat not easier pass through the wall of thermos.

Double walled tube coated with shiny paint

Shiny surface reflect heat from the wall of thermos flasks back to water.so the water remain hot.

Double walled made of glass Glass is bad conductor.it will reduce heat loss. 48. Explain how the design of radiator of the car and characteristic of cooling agent which can

absorb heat at short time,

Increase the length/area of cooling coil Can transfer the heat faster to the surrounding Increase the number of fin blades Can cool down faster

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Use larger fan Can cool down larger area Use cooling agent liquid with greater

boiling point It won’t boild easily in high temperature Use cooling agent liquid with higher

specific heat capacity

Able to absorb large amount of heat

CHAPTER 5

49. Determine and explain in the build of magnifying glass to be use for enlarging the image of stamp

Choose convex lens The image will magnify Excellent clarity of lens The image is clearer Small focal length Able to focus nearer

Medium diameter of lens Able to be hold by hand to identify the stamps The object is place less distance than

focal length The image form is magnify, virtual and upright 50. Explain the suitability of the mirror that be use in shop to watch over the customer

Use convex mirror Wider field of view Greater reflectivity of material Clearer image

Choose a bigger size of mirror Enable wider view and sharper image Place the mirror at the corner of shop

ceiling Easier to look at and won’t disturb the customer pathway

Low density Lighter to hang up

51. Design fibre optic

Use refractive index of outer layer is less

than the refractive index of inner layer So that total internal reflection can happen in the fiber optic. Use high flexibility material so that it can be bend easily

Use strong material do not break easily

Use thin material Lighter // can be use in small area Low density material Lighter

52. Determine and explain the build of microscope using lens P and Q with focal length of 15 cm and 5 cm respectively. Suggest modification that need to be done to get brighter ang bigger image.

Suggestion Explaination

P as eye piece and Q as objective lens Focal length of P is longer than Q

Fo < u <2fo To produce real, inverted and magnified image Adjusted so that u < fe To produce virtual. Inverted and bigger image//

to acts as a magnifying glass

Distance between lenses > fo + fe To produce bigger image from the eyepiece // to increase the magnification

Store in a cool and dry place To avoid formation fungus at the lenses Use more powerful// shorter focal length

lenses

To produce bigger image Use a lamp near the object// use bigger

diameter of objective lens To produce brighter image

53. Explain the suitable characteristic of the mirror to be use as outdoor safety mirror at the corner of the road

Use convex mirror Wider field of view

Excellent weather resistance Able to withstand bad weather Excellent impact resistance of material Save cost, everlasting

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Greater reflectivity of material Clearer image even in bad weather Place at the sharp road corner , at

bending road To minimize from accident occur, to enable motorist see the oncoming traffic Small roof Protect from rain drop for better image 54. Detemine and explain the build of Astro disc using appropriate physics concepts.

Choose convex curve parabolic The signals come can be focus at one point All signal are focus on focal point Better reception

Smooth surface of disc Better reflection Locate the disc at high and facing towards

satellite No obstacle, better signal

Clean surface of disc, no water drop or dirt Better reflection, almost 100% reception receive by feed horn

55. Modified the slide projector that need to be place in school hall and can be seen by many student with clearer image.

suggestion Explaination

Use higher power bulb Higher intensity of light or more light produced The filament of the bulb is at the focus

point of the concave mirror The light focuses at one point. // parallel ray can be obtained after reflection by concave mirror

More curvature More light to be reflected (upward) // less light toward other direction other than upward Lens between f and 2f To produce real ang enlarge or bigger images Increase the distance or further away the

screen Larger image produced

Electric fan operates during and after the

lamp is switches on Cooling system to stabilized the temperature (heat energy produced by filament bulb) to increase the projector lifetime

Use condenser mirror To concentrate more light to the slide Use a concave mirror instead of plane

mirror Focus the light directly to the lens // increase the intensity og light Place the filament at centre of curvature

of the converging mirror // use high powered lens

Light goes directly from the lamp and reflect back on the same path // increase the intensity of light toward the transparency // to get brighter image

Use heat filter To absorb excess heat to the transparency

56. Determine and explain the build of telescope using lens J and K with lens K is thicker than lens J which produce bigger and clearer image.

Suggestion Expalanation

 C hoose lens K as eyepiece lens

Lens K is thicker than lens J 

Light ray is refracted more in lens K than lens J, focal length of lens K is shorter than lens J

 Therefore the thickerthe lens, the greater the refraction of light and with that the shorter the focal length of a lens will be  Choose lens J as objective lens

Use bigger diameter lens as objective lens

Characteristics of objective lens for telescope is

 Has larger surface area which allow more light enter

 Has a longer focal length Use low power convex lens as the

objective lens Low power lens has a longer focal length ,fo  Magnification of telescope =f0/fe higher, magnification higher

Use high power convex lens as the eye

lens High power lens has a shorter focal length,fe higher, magnnification higher Use bigger diameter of objective lens More light permitted to enter the telescope

and a clearer image is seen CHAPTER 6

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57. Design a good beach

near the bay divergence of the waves energy /calmer High retaining walls Over flow

To reflect the waves from the shore

Reduce direct impact of the waves on the shore

Wall from concrete reduce erosion are built

Concrete barrier structure with a gap Waves passing through the gap will be diffracted in the children’s area.

-reduce amplitude Tambak laut supaya lebih cetek Reduce speed

More number of tree Diffraction occur will reduce tha amplitude Uneven surface of retaining wall Reduce energy

58. Suggest and explain how ordinary fishing boat can be upgrade to the new boat which complete equipment to detect the crowd of fish.

Attach radar system to the ship a) Ultrasonic transmitter

This equipment needs to detect crowd of fish and for measurement the depth of the crowd of fish

-Use to produce ultrasonic pulses a) Microfone reciever To detect ultrasonic pulses

b) CRO -To measure the depth of fish by calculating d=vt/2; d=depth, v=velocity, t=time

Use ultrasonic wave -Ultrasound not produce sound

-Ultrasonic wave has higher frequency, more energy, so it can move further

Use high energy wave The penetrating power is higher 59. Explain the suitable design or method to build quality concert hall.

Cover the hard wall with soft board or thick curtain

Soft surface can absorb sound and reduce reflection of sound

Place the wall with hole or egg carton design

Can reduce reflection of sound so sound will be clearer/reduce echo

Fixed 2 loud speaker in concert hall Loud speaker can act as coherent sources for constructive inteference

Arranged the sit at antinodal place Strong sound can be heard Use glass or mirror hall which is the type

which are not easily broken Sound with high frequency might break the glass Use special computer to generate sound

wave which produce destructive inteference

Audience can enjoy better presentation without disturbance

60. Explain the suitable design of retaining wall to protect the ship at the harbor

Suggestion Explaination

Build concrete retaining wall Can withstand impact of the wave, difficult to crack

Retaining wall should be curved and uneven surface

Prevent reflection of wave back to the ship Build retaining wall in front of the bay The wave are calmer at thr region

Retaining wall has gap Diffraction will occur The gap at retaining wall is

narrow( smaller than wave length) The greater the curvature of wavefront will occur. Amplitude after passing gap is smaller There are slope at the bottom of retaining

wall

At shallow region, the wavelength of wave is smaller, so the velocity of the wave smaller Retaining wall should be build higher To ensure no spill over of wave

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61. Explain the characteristics of parabolic radar system to detect signal from satellite communication.

Large diameter size of parabolic disc Able to receives more electric signal Type of wave transmited is Microwave Has high frequency, high energy, short

wavelength so it is easy to be reflected The distance of the signal receiver from

the centre of parabolic disc is the same as the focal length

The signal can be focus to the centre of the parabolic disc

Place parabolic disc higher from the ground

The signal with not be block by trees or anything and the signal easy to be detected Place parabolic disc at clearplace No signal disturbance

CHAPTER 7

62. Suggest the suitable lamp that can be use in the library, cheaper yet become the room brighter

Lamp with parallel circuit If any lamp were burn out, others can still be used

Attach shiny reflector Can reflect light more, no need to install more lamp, the room will become brighter.

Low power lamp Safe cost

High efficiency lamp // fluorescent The room looks brighter Long life span lamp No need to replace often

Low price lamp Save money

63. Explain the modification of menthol bulb lamp to efficient lamp to be use in study room.

Use the fluorescent lamp not a filament bulb

Fluorescent lamp use less power and economic (consume less power) compare to filament bulb. Bigger cover with white colour Less reflection on eyes and absorb less heat

energy and good heat reflector

Use the adjustable stand or portable The height of the lamp can be adjusted can be used anywhere

Connect with the earth wire Avoid short circuit and damage on the bulb Use an energy saver lamp Produce same brightness with less power

consumption

64. Suggest the suitable design of fuse to protect an electrical equipment which is label 240V,2400W

Thin fuse wire Less space/to carry a limited electrical current/less mass hence low heat capacity/shorter time to heat up to melting point and blow

Ceramic cartridge Can withstand higher temperature because spark created by high voltage.240V can be huge

Fuse rating is 13A Maximum rating must be sligthly higher than normal current

Low melting point For fast blow/melting faster when excessive current flow/easy to cut the current flow

Low specific heat capacity The fuse wire easily heated,melt and break the circuit

Metal is used Good electric conductor

Resistance to oxidation Does not interface with other function

65. You have to choose one of the cables to be used in the National Grid Network. Explain the suitability of each of the characteristics of the cables.

Diameter should be large To reduce the resistance of the cable density should be low The cables will be lighter and can be

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supportedsecurely

The rate of expansion should be low So thre is less expansion and less sagging in the cables during hot days

The melting point should be high So the cables does not melt in high temperature

66. Explain the characteristic of electric pylon and the cable taht been use for electric transmission

Material: steel alloy Strong,will not break easily V shape steel alloy Not too heavy

Trust and supprt join Can support bigger weight Made from small diameter and laminated

wire Reduce addy current

Cable made from low density material Cable is not heavy/ light weight

67. Investigate the characteristic of electric oven that can toast more cupcakes at less time

The space inside oven is build bigger It can fil up 180 slices of bread Increase the number of resistance heater

at the top and bottom

So it can supply enough heat

The wall is made of good insulator Tyhe heat will not lost to surrounding

Fix a fan inside the oven Heat energy releaswed can spread uniformly in oven

Internal space of oven is painted silver So the heat will radiated at wall and reflected back completely

Fix the step up transformer Oven can receive higher voltage and can function with higher power

68. Explain the designof electric kettle

Material of heating is made from nichrome To produces high heat energy

High number of loop To increase surface area so that more heat is released

Use high power To produce more heat energy in the coil High melting point coil Nit easy melt under high temperature Low rate of rusting Does not get rust easily

Use thermostat When temperatures reach 100o_C

3 plug in If short circuit the overload current flows to earth(for safety reason)

69. Design incubator used to hatch eggs

Parallel circuit When one bulb damage the another bulb still function/heat can distributed uniformly

Multi storey rack More eggs can be arranged Using fan heat can distributed uniformly Bulb with same brigthness and

power heat can distributed uniformly

Using alarm To ensure that correct timing is employed in the hatching of eggs

70. Design circuit for cabin or house

connected in parallel Allow each electric appliances to be switched on and off independently

Fit fuse at the live wire in the fuse

box high voltage of electric current flows through theTo stop the flow of current by melting when a circuit // switches itself off very quickly if the current exceeds e.g. 15A (for 15A mcb)

Earth connection to the metal case of

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and the earth wire, the fuse in the live wire will blow and cut off the supply. It will protect a person who may touch a faulty or live appliance

Use low power lamps / install fluorescent lamp

To save the energy Regularly cleaning and removing dust

from the air filters of air conditioners// Do not put more water in a kettle than needed for hot drinks

To save the energy

CHAPTER 8

71. Suggest modification that need to be done on dc motor to increase efficiency of the motor.

Low density material Coil hass smaller mass/ lighter Increase the number of

turns in the coil

Can increase magnitude of force/ higher electromagnetic field strength

Use high strength of magnets/ Add more magnets

Increase the strength of magnetic field More segments Coil rotates smoothly

Increase the magnitude of current

Can increase the magnitude of force/ can increase the strength of magnetic field

72. Investigate the design and the characteristic to improve the efficiency of transformer.

Use soft iron core Easy to magnetized and demagnetized Laminated core Less eddy current or reduce energy lost Use thick wire Reduce the resistance or more current flow Use copper wire to make coil Low resistance or reduce the lost of heat Wind the secondary coil on top of the

primary coil

Reduce leakage of field lines

73. How to design a moving coil ammeter that can function better and able to detect small change of current?

Use stronger magnet Strong magnetic field or larger rotation

Use curve magnet or concave Produce radial magnetic field/to get linear scale Use cylindrical core To supply uniform magnetic field

Use soft iron core To concentrate the magnetic field Use linear scale The angle of rotation is linear The sensitivity of moving coil

galvanometer can be increased by increasing the strength of the radial magnetic field

Increase the force between the current carrying coil and magnetic field

Using hairspring of lower stiffness

Smaller opposing force to stop turning of coil Use lighter pointer Smaller inertia easier to move

Use a coil of a lighter mass Smaller inertia able to move easily

Increase the area of coil More changes of magnetic flux,a bigger force are produce

74. Suggest and explain the build of adaptor to charge the 8V handphone from 240V power supply.

Use step down transformer Able to reduce voltage

Ratio of turns 30 : 1 // 240V:8V Can reduce voltage from 240V to 8V Use four diodes Full wave rectification

Full wave rectifier To convert au current to dc current

Using a capacitor To smooth output current (steady direct current CHAPTER 9

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75. Suggest and explain the build of adaptor to charge the 8V handphone from 240V power supply

Use step down transformer Able to reduce voltage

Ratio of turns 30 : 1 // 240V:8V Can reduce voltage from 240V to 8V Use four diodes Full wave rectification

Full wave rectifier To convert au current to dc current Using a capacitor To smooth output current (steady direct

current

76. Consult and modified the automatic switch light (diagram A) above which can switch on at night and switch off during morning to be automatic switch on fire alarm when there are fire , explain using diagram and the function of component.

Change R1 to termistor Thermistor can be detect heat from fire Change LED with alarm// siren Able to produce sound of alarm if fire is

detected

Change LDR with R1 During fire, R1 has greater resistance compare to LDR so, no current flow

When the temperature is high, the resistance of thermistor is low. This will increase the voltage acroos R1. So, currnt will flow to the base of transistor , than the transistor is switch on followed by greater increase in collecter current. The alarm will switch on.

77. Suggest the modification need to be done to the circuit in Diagram C so that it can function as automatically fire alarm switch that need high voltage.

Suggestion Explanation Replace LDR with thermistor To detect heat when temperature is high Replace bulb with siren/bell To produce sound

Connect relay switch to output transistor To switch on the siren Interchange the position of resistor R and

thermistor To increase base voltage//voltage across R//base current Use 240 V power supply Siren is function as high voltage

78. Modified the circuit 240V and Np = 4000 turns circuit to switch on 12V d.c radio.

Step-down transformer Capable of reducing potential difference / voltage

Ratio of turns 20 :1 // 240:12 Np = 4000

turns and Ns = 200 turns Reduce potential difference 240V to 12V Using four diodes Full wave retification

Using a capacitor To smooth out output current // produce output to steady direct current.

79. Moving coil microphone

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Suggestion Explanation use thin diaphragm Easy to vibrate

Use strong material Not easy to break

More number of turns of coil Increase the rate of change of magnetic flux linkage // The magnitude of the induced current or is also increased

Thicker diameter of wire of coil reduce the resistance of the coil

Using more powerful magnet to increase the strength of the magnetic

field.//Increase the rate of change of magnetic flux linkage//The magnitude of the induced current or induced electromotive force is also increased CHAPTER 10

80. Explain the suitability of characteristic of radioisotopes to be used as treatment in brain tumor radiotherapy?

Short half life Radioactive is dangerous substance, short half lfe can decay faster

Gamma ray radiation Gamma can kill cancerous cell and can penetrate skin of patient

Low ionozing power Minimum damage to tissue organ Liquid state of matter Easy to dissolve

High penetrating power Can penetrate easily

81. Suggest and explain the safety ways, which are required when handling radioactive substance.

Use thick lead box Radioactive rays evem gamma cannot pass through

Use forceps / robotic hand Avoid direct touch

Wear photographic film Able to detect exposure radiations

Wear plumbum safety suit To protect the body from expose to radiation

Use siren Faster warning when leakage

Packed into concrete drum and buried underground

Prevent the radioactive waste discharge to environment

Always place GM detector nearby To detect the amount of radioactive nearby, for safety

Label the radioactive container with

symbol Easy to detect radioactive substance

82. Explain the suitability of characteristic odf radioisotope to be use in controliing the population of pest

Use gamma ray Able to mutate the insect Solid state of matter Easy to handle

Long half life Last longer

High penetrating power Able to penetrate thick object/material High ionizing power Able to change// mutate the biology of insect 83. . Explain the suitability of characterisitc of radioisotopes to be used in th trace of water

pipeline.

Short lhalf life Radioactive is dangerous substance, short half life can decay faster

Few hour half life - Enough time for worker to detect the pipe leakage

- Radioactive uis dangerous

Beta particle or Gamma ray radiation Can penetrate pipe and soil, can be detected Liquid state Can be inject and dissolve into water

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Suggestion Explanation Use uranium-235 Use as nucler fuel

Nuclear fission A lot of heat will produce

Boron or Cadmium rad use as control rods To control the rate of nuvlear fission and to stop the radiation

Use moderator (graphitr) To slow the motion of neutron to the best reaction rate. So the rate of nuclear fission can be

controlled

Bulid thick concrete wall Lead or thick concrete wall can prevent the escape of radioactive rays, keep the radiation inside the reactor

Coarbon dioxide or water is use as coolong

agent To remove heat of reaction for turbine generator. This produce steam as heat carrier Use steam To turn the turbine and able to generate current

85. Explain the suitability of charactersitic of radioisotopes to be used in sanitiza medical equip,ent

Gamma ray Able to kill ant virus/ bacteria

Longer half life No need to change radioactive frequently Silid state of matter Easy to handle

High penetrating power Able to penetrate any equipment to sanitize

86. Explain the suitability of characteristics of radioisotope to be used in detecting the position of blood clot in veins (Deep vein thrombosis)

87. E

xplain the suitability of characteristics of radioisotope to be use in the trace of blockage in the kidney patient.

Use Iodine-123 Used as nuclear imaging tracers to evaluate the anatomic and physiologyc function

Gamma ray Able to penetrate trough body, bones and be detected

Low energy Do not cause serious damage in cells Liquid state of matter Easy to inject to patient body

Short half life Active in body in short time

88. Explain the suitability of characteristics of radioisotope to be use in control the thickness of paper in factory

89. Explain the suitability of characteristics of radioisotope to be use in control the thickness of aluminium sheet in factory.

Long half life Can be used for long time, no need to replace frequently7 so, it save cost

Gamma ray Can be penetrate aluminium sheet and be detected

Solid state of matter Easy to handle, does not spill

Use liquid state of matter Able to inject into patient body, dissolve easily Short half life Active in body in short time

Use beta ray Able to penetrate skin

Low ionizing power Minimum damage to tissue organ

Long half life Can be used for long time, no need to replace frequently so, it save cost

Beta ray Can penetrate paper and be detected Solid state of matter Easy to handle

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MAKING DECISION-SECTION C

90. The transmission of electricity over the National Grid Network uses high voltage cables. You are assigned to study the characteristics of cables which could be used as transmission cable. Table 12 shows the characteristics of four transmission cables. Determine the most suitable transmission cable to be used and give reasons for your choice.

Cable Resistivity /Ωm1 - Density / kg m-3 _Cost _{Rate of thermal expansion}

P 3.0 x l0-7 _{5 x l0}5 _Low _High Q 1.8 x l0-8 _{2 x l0}3 _Medium _Low R 7.5 x l0-7 _{8 x l0}2 _High _Medium S 7.0 x l0-8 _{4 x l0}3 _Medium _High Jawapan Characteristic Explanation

Low resistivity To reduce heat loss in the cables Low density The cables will be lighter Low cost Cost of project will be lower Low rate of thermal expansion The cables will not expand under hot weather Cable Q Low resistivity, low density, medium cost, low rate

of thermal expansion

91. You are required to build a hydrometer that can be used to measure densities of

concentrated acids.Table 11.1 shows the characteristics of 4 types of hydrometers L, M, N and O. Decide which hydrometer is most suitable and give reasons.

Hydromet er Type of material of hydrometer Diameter of capillary tube/ cm Density of

shots/ kgm-3 Diameter of _{bottom bulb/ cm}

L Plastic/Plastik 0.5 1000 1.0 M Plastic/Plastik 2.0 1300 3.0 N Glass / kaca 0.5 9800 3.0 O Glass/ kaca 2.0 8000 1.0 Jawapan Characteristic Explanation

Material made from glass Glass does not corrode with acid

Small diameter of capillary tube To increase the sensitivity of the hydrometer High density of shots Makes the hydrometer stays upright

Big diameter of bottom bulb To obtaine a bigger upthrust.

Choose N N is made from glass, has small diameter of capillary tube, high density of shots and a big diameter of bottom bulb

92. As a researcher , your duty is to study the characteristics of a material to make a water heater. You are given four choices of metal type T, U,V and W. The table below shows the characteristics of the four metals.Determine the most suitable metal to be used as the material to make the heater and give your reasons.

Jawapan

Smaller surface area the resistance is higher High melting point not easy to melt

Low specific heat capacity the temperature arises shortly Long (coiled) metal to increase the resistance

Choose V because it has,smaller surface area, high melting

Metal

The cross sectional area Melting Point Specific Heat Capacity Length

T Smaller Low High Long

U Larger High Low Short

V Smaller High Low Long

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point, low specific heat capacity and long metal 93. You are given four choices of metals P, Q, R and S. The table below shows the characteristics

for the four metals. Determine the most suitable metal to be used as the material to make the boat and give your reasons.

Metal Shape Density Specific Heat_Capacity Strength

P Streamlined 900 Low High

Q Oval 452 High High

R Circle 387 Low High

S Streamlined 500 High High

Jawapan

Characteristic/cirri Reason/Sebab

Streamline / larus reduce the resistance of water/ Density /ketumpatan rendah higher buoyant force/ daya apungan

tinggi

Specific heat capacity high / absorbs heat slowly/serap haba dengan perlahan

High strength / Kekuatan tinggi Difficult to damage / sukar rosak

Choose S because its streamline,low density, high specific heat capacity and high strength

94. A student plans to fix a lamp in his room. Table 12.1 shows the features of 4 different types of lamps. Explain the suitability of each feature in Table 12.1 and then determine the most suitable lamp to be used. Give a reason for your choice

Type of lamp Power Efficiency Life Span Price Compact fluorescent

lamp 18 W 50 % 7000 hours High

Filament lamp 75 W 12 % 1000 hours Low

Long fluorescent lamp 20 W 45 % 14000 hours Medium Round fluorescent lamp 24 W 40 % 10000 hours High Jawapan

Low power lamp Safe cost//electric bill

High efficiency The room looks brighter//high output power//less power wastage

Long life span No need to replace often

Low price Save money/cost

Long fluorescent Low power with highest efficiency, long hours of life span and low price

95. Table 11.1 shows 5 materials which can be used to make an optical fibre. You are asked to investigate the characteristics of the materials in Table 11.1 which could be used to make the optical fibre.

Explain the suitability of each characteristic and hence, determine the most suitable material to be used to make the optical fibre. Give a reason for your choice.

Material Refractive index % of light energy absorbed Rigidity Strength P 1.75 2 % Strong Weak Q 1.80 10 % Weak Strong R 1.70 2 % Weak Strong S 1.52 3 % Strong Strong T 1.48 10 % Weak Weak Jawapan Characteristic Explanation

High refractive index Total internal reflection can occur easily Small amount of light energy being

absorbed by the material The object under observation can be seen clearly //more light can be transmitted Material with weak rigidity The optical fibre can be bent easily

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Material with great strength The optical fibre can last longer/not easily spoil Material R High refractive index, low % of light energy

absorbed, weak rigidity and great strength 96. You are asked to investigate the characteristics of hot air balloon as below. Explain the

suitability for each characteristic for the hot air balloons and then determine which hot balloon will move up the fastest into the air. Give a reason for your choice

Jawapan

Characteristic Explaination

Volume of the balloon is high Displace a larger amount of air/ Produce a higher buoyant force. Density of the balloon material is

low

Lower mass/Light

Gas temperature is high Produce a maximum expansion of balloon. Total of mass is low Upwards resultant force is higher/ Balloon move

upwards faster.

Choose Q Because it has a high volume,the density of the balloonmaterial is low,the gas temperature is high and the total mass is low.

97. Table 11.1 shows the characteristics of five types of materials that can be used for making the soles of the trekking shoes. You are asked to study the characteristics of the materials shown in Table 11.1. Explain the suitability of each characteristics in Table 11.1 and then determine the most suitable material to be used. Give a reason for your choice.

Type of material

Density (Kg/m -3₎

Number of studs x Area of 1 stud Expansion effect Ability to stretch P 820 6 x 30 cm2 _Low _Good Q 700 8 x 30 cm2 _Low _Good R 720 5 x 30 cm2 _Medium _Average S 750 4 x 30 cm2 _High _Poor T 880 3 x 30 cm2 _High _Poor Jawapan Characteristic Reasons

Low density Small mass/light Many/fewer/very few studs Gives extra/higher grip

Expansion effect is low Always fits/Does not loosen when hot.

Ability to stretch is good Less stress on the feet/Can be pushed in all directions/ Can walk on uneven surface.

The most suitable material is Q Because it has a low density,many studs,low expansion effect and good ability to stretch.

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98. Table 12.2 shows the characteristics of five radioisotopes P, Q, R, S and T. As a factory

engineer, you are required to determine the most suitable radioisotope that can be used by the system to ensure the volume of guava juice is uniform.Study the characteristics of all 5

radioisotopes and explain the suitability of the aspects.Determine the most suitable radioisotope and give the reason for your choice.

Radioisoto pe Radioisoto p Half life Separuh hayat Types of ray Jenis sinar State of matter Keadaan jirim Ionising power Kuasa pengionan

P 7 hours alfa solid high

Q 10 days beta liquid moderate

R 100 days gamma solid low

S 10 years gamma liquid high

T 30 years beta solid low

Jawapan

99. You are assigned to investigate the design for the location to keep the boats and the

characteristics of the retaining wall as shown in Diagram 12.2 based on the following aspects: - the location to keep the boat

- material used for the retaining wall - the height of retaining wall

- size of slit

Explain the suitability of the location and the characteristics of the retaining wall and determine the most suitable design to keep the boat safely.

Jawapan

Characteristic Reasons

Bay Wave is calmer

Concrete retaining wall Stronger/ / lasting

High wall Prevent high wave

Smaller opening/aperture / slit of retaining wall

Diffraction obvious //low wave energy

Choose P At bay, concrete retaining wall , high wall and smaller _slit

Characteristics Explanation

Has a long half-life Can be used for a long time hence save cost Emits beta Can penetrate box and liquid and is less

dangerous than gamma Solid form Easy to handle and contain.

Low ionising power Does not change the state and taste of juice.

Radioisotope T It has long half life, emits beta, in solid form and has low ionising power.

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100. Diagram 11.4 shows five designs of ‘Newton’s Cradle’, P, Q, R, S and T, with different specifications. You are required to determine the most suitable design to make the ball at the end swings up to higher level and at bigger speed. Study all the five designs from the following aspects:

− The arrangement of the balls − The type of material used to make the balls

− the number of string used to hang the balls − the position of the ball to start the oscillation

Jawapan

Characteristic Reasons

The balls touch each other This will reduce losses of energy which will reduce the speed of the

balls The type of material used to

make the balls is steel

Steel balls are hard and produce highly elastic collision. Energy can

easily propagates through the intermediate balls. Two strings used to hang each

ball This string arrangement restricts the balls’ movements to the same plane. the position of the ball to start the oscillation

High position of the ball High potential energy and will change to high kinetic energy. The last end ball will swing at bigger speed.

The most suitable design is Q because the ball s touch each other, made from steel, use two strings attached to each ball and the initial position of the ball is high