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CHAPTER 1 : INTRODUCTION TO PHYSICS
1.1 Understanding Physics
Mechanical Energy
PHYSICS
Study of the natural phenomena and the properties of matter. Solid Liquid Gas Mechanical Energy Heat Energy Light Energy Wave Energy Electrical Energy Nuclear Energy Chemical Energy Relationship with matter Properties of Energy Relationship with energy Properties of Matter forms states Matter Energy Mechanics Properties of matter Heat Light Wave in the fields of Electricity & Electromagnetism Atomic Physics & Nuclear Physics Electronics
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1.2 PHYSICAL QUANTITIES
Base quantity
1 A physical quantity is ……….. 2 Examples of scientific instruments :……… 3 A base quantity is a physical quantity which cannot be defined in terms of other physical
quantities.
4 Study the following picture and list the physical quantities that can be measured.
5 List of 5 basic physical quantities and their units.
Base quantity Symbol S.I. Unit Symbol for S.I. Unit
Length Mass Time Current Temperature
6 Two quantities that have also identified as basic quantity. There are : i) ………..unit …………..
ii) ………. unit ………..
The list of physical quantities :
1. ………. 2. ………. 3. ………. 4. ………. 5. ………. 6. ………. 7. ………. 8. ……….
any quantity that can be measured by a scientific instrument.
stopwatch, metre rule balance,thermometer,ammeter etc. Height, mass, size, age, temperature, current Power, Thermal energy l meter m m kilogram kg t second s I Ampere A T Kelvin K
Light intensity candela Amount of substance mol
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Standard Form
1 Standard form = A x 10n , 1 ≤ A < 10 and n = integer no.
2 Standard form is used to ………... 3 Some physical quantities have extremely small magnitudes. Write the following
quantities in standard form :
a. Radius of the earth = 6 370 000 m =………. b. Mass of an electron = 0.000000000000000000000000000000 911 kg =………... c. Size of a particle = 0.000 03 m = ……… b. Diameter of an atom = 0.000 000 072 m = ………... c. Wavelength of light = 0.000 000 55 m = ……….. Prefixes
1. Prefixes are usually used to ………... 2. It will be written ……… 3. The list of prefixes :
Tera (T) Giga (G) Mega (M) kilo (k) mili (m) micro () nano (n) pico (p) 1012 109 106 103 100 10-3 10-6 10-9 10-12 Hekto (ha) Deka (da) desi (d) centi (s) 102 101 10-1 10-2 Eg : 1 Tm = ………. 3.6 mA = ………. How to change the unit ;
Eg :
1. Mega to nano
2. Tera to micro
3. piko to Mega
simplify the expression of very large and small numbers
6.37 x 106 m
1.673 x 10-27 kg 3.0 x 10-4 m
7.2 x 10-8 m 5.5 x 10-7
represent a large physical quantity or extremely small quantity in S.I units.
before the unit as a multiplying factor.
1 x 1012 m 3.6 x 10-3A 1.33 MA = 1.33 x 106 A = 1.33 x 10 6-(-9) nA = 1.33 x 10 15 nA 1.23 Tm to unit m unit 1.23 Tm = 1.23 x 10 12m = 1.23 x 10 12 – (-6)m = 1.23 x 10 18m 5456 pA to MA unit 5456 pA = 5.456 x 10 3 + (-12) pA = 5.456 x 10 -9pA = 5.456 x 10 -9 –(6) MA = 5.456 x 10 -15 MA
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4. Some physical quantities have extremely large magnitudes. These extremely large and small values can be written in standard form or using standard prefixes. Write the quantities in standard prefixes:
a. Frequency of radio wave = 91 000 000 Hz = ………. b. Diameter of the earth = 12 800 000 m = ……… c. Distance between the moon and the earth = 383 000 000 m = ……… d. Mass of the earth = 6 000 000 000 000 000 000 000 000 kg = ………
Derived quantities
1 A derived quantity is …….……… ……… 2 Determine the derived unit for the following derived quantities.
Derived
quantity Formula Derived unit
Name of derived unit
area area = length x width m x m = m2 –
volume volume = length x width x height m x m x m = m3 –
density volume mass ensity d 3 kgm 3 m kg – velocity time nt displaceme elocity v 1 s m s m –
momentum momentum = mass x velocity kg m s-1 –
Acceleration time velocity in change on accelerati 2 1 1 -1 s m s s m s s m –
Force force = mass x acceleration kg m s-2 Newton (N)
pressure
area force pressure
weight weight = mass x gravitational acceleration
work work = force x displacement
power
time work power
kinetic energy K.E massvelocity2
2 1 kg m s-2 / m2 kg m-1 s-2 (Nm-2) kg ms -2 Newton (N) N m Joule (J) J s -1 Watt (W) Kg ms-2 Joule (J) 9.1 x 101 MHz 12.8 Mm = 1.28 x 10 1 Mm 383 Mm = 3.83 x 10 2 Mm 6.0 x 10 12 Tm
a physical quantity which combines several basic quantities through multiplication, division or both
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Derived
quantity Formula Derived unit
Name of derived unit
potential
energy P.E = mass x gravitational acceleration x height Kg ms
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Joule (J)
charge charge = current x time Ampere second
(As) Coulomb (C) voltage charge work voltage J C-1 Volt (v) resistance current voltage resistance v A-1 Ohm (Ω)
Note that the physical quantities such as width, thickness, height, distance, displacement, perimeter, radius and diameter are equivalent to length.
1.3 SCALAR AND VECTOR QUANTITIES
1 Scalar quantities are ……… Examples : ……… 2 Vector quantities are………...
Examples : ……… 3 Study the following description of events carefully and then decide which events require
magnitude, direction or both to specify them.
Description of events Magnitude Direction
1. The temperature in the room is 25 0C
2. The location of Ayer Hitam is 60 km to the
north-west of Johor Bahru
3. The power of the electric bulb is 80 W
4. A car is travelling at 80 km h-1 from Johor Bahru
to Kuala Lumpur
1.4 MEASUREMENTS
Using Appropriate Instruments to Measure
1 There are various types of……….
2 We must know how to choose the appropriate instrument to ……….. Quantity which has only magnitude or size
Mass, Length, Speed, volume
Quantity which has magnitude or size and direction. Velocity, Force, Displacement, Acceleration
Ý
Ý Ý Ý Ý Ý
measuring instrument with different measuring capabilities. measure a particular quantity.
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3 Examples of instrument and its measuring ability.
Measuring instrument Range of measurement Smallest scale division
Measuring tape
Meter rule
Vernier caliper
Micrometer screw gauge
4 Sample of measuring instruments :
4.1 Ammeter : ………..
4.2 Measuring cylinder : ………...
4.3 Ruler : ……… wrong right wrong
10 11 12 13 14 15 Reading = ……… cm
4.4 Vernier calliper
A venier calliper is used to measure :
a. ………b. ………. c. ………d. ………. A vernier calliper gives readings to an accuracy of ………...…. cm.
pointer mirror pointer mirror
Pointer’s image is behind the pointer incorret reading correct reading 1 2 3 0 4 1 2 3 0 4
Pointer’s image can be seen
Right position of eye (eye are in a line perpendicular to the plane of the scale)
wrong position of eye
wrong position of eye
water
is use to determine the volume of liquid.
is use to determine the length
2.5 cm
small object depth of a hole
external diameter of a cylinder or pipe internal diameter of a pipe or tube 0.01cm
Up to a few meters 0.1 cm
1 m 0.1 cm (0.01 m) 10 cm 0.01 cm
less than 2 cm (20 mm) 0.001 cm (0.01 mm)
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Length of vernier scale = ……… cm Vernier scale is divided into 10 divisions Length of the divisions = ………. cm
The diagram below shows a vernier calliper with reading.
Vernier calliper reading = ………. cm 4.5 Micrometer screw gauge.
A micrometer screw gauge is used to measure : a. ……… b. ………. c. ……… 0 5 10 0 1 0 1 0 5 10 Main scale in cm Vernier scale cm 0 1 2 3 4 SKALA UTAMA 0 5 10 inside jaws Vernier scale outside jaws Main scale 0 1 2 3 4 5 6 7 8 9 10 0 1 cm Main scale = ………. Vernier scale = ……….. Final reading = ………..
Find the division of vernier scale which is coincides with any part of the main scale
Anvil spindle sleeve (main scale)
thimble (circular scale)
ratchet
frame
One complete turn of the thimble (50 division) moves the spindle by 0.50 mm. Division of thimble = ……….. = ……….. A accuracy of micrometer screw gauge = ……….. Sleeve scale : ……… Thimble scale : …………. Total reading : …………..
The differenct between the main scale and vernier scale is = ………. cm
0.15
objects that are small in size diameter of a wire
diameter of small spheres such as ball bearings
0.5 ÷ 50 0.01 mm 4.5 mm 0.01 mm 0.22 mm 4.62 mm 1.0 0.01 0.01 cm 0.2 cm 0.06 cm 0.26 cm
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Example :
4.6 Some others measuring instruments :
……… ……… ……… ………..
………. ……….. ………
Hands-on activity 1.1 on page 1 of the practical book to learn more about choosing appropriate instruments.
Exercise: Vernier Callipers And Micrometer Screw Gauge
1. Write down the readings shown by the following (a) (b) Sleeve scale : ……… Thimble scale : …………. Total reading : …………... 0 5 10 7 8 0 5 10 4 5 A B Q P Answer: …7.89 cm………….. Answer: …4.27 cm………….. 2.0 mm 0.22 mm 2.22 mm
Analogue stopwatch digital stopwatch thermometer miliammeter
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(c)
(d)
2. (a) The following diagram shows the scale of a vernier calliper when the jaws are closed.
Zero error = …0.02……… cm
(b). The following diagram shows the scale of the same vernier calliper when there are 40 pieces of cardboard between the jaws.
3. Write down the readings shown by the following micrometer screw gauges. (a) (b) Answer: ………6.87 cm……… Answer:……12.32 cm………….. 0 5 10 0 1 0 5 1 0 6 7 0 5 10 5 6 0 5 10 0 1 Answer: ……6.28 cm……….. Answer: …0.02 cm………….. Reading shown = …5.64…….cm Corrected reading = …5.62……..cm 35 40 0 5 30 0 5 10 35
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(c) (d)
Answer:………4.71 cm……… Answer:……9.17 cm………
4. (a) Determine the readings of the following micrometer screw gauges.
Zero error = …- 0.02…….. mm Zero error = …+0.03…….. mm (b) Determine the readings of the following micrometer screw gauges.
5. Write down the readings shown by the following micrometer screw gauges. (a) (b) Answer: …6.88 mm………… Answer: …..12.32 mm…… (c) (d) Answer:………4.71 mm………… Answer: 9.17 mm………… 20 25 0 0 0 45 5 0 0 5 0 0 0 5 15 20 15 20 0 5
Zero error = +0.03………mm Reading shown = 6.67………..mm Corrected reading = 6.64………..mm 35 40 0 5 30 0 5 10 35 20 25 0 15 20 0 5
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Accuracy and consistency in measurements.
1. Accuracy : ……… 2. Consistency : ……… 3. Sensitivity : ……… ……… ……… ……….. ……….. ……….. ……… Hands-on activity 1.2 on page 2 of the practical book to determine the sensitivity of some measuring instruments.
Errors in measurements
1. All measurements are values ……… 2. In other word, it is a matter of ……… 3. This is because ……… 4. Two main types of errors:
4.1 ……… Occurs due to : a) ……… b) ……… c) ……… Examples : a) ……… b) ……… c) ……… target target
The ability of an instrument to measure nearest to the actual value
The ability of an instrument to measure consistently with little or no relative deviation among readings.
The ability of an instrument to detect a small change in the quantity measured.
consistent but inaccurate consistent and accurate inaccurate and not consistent
Accuratebut not consistent inaccurate but consistent inaccurate but not consistent
of approximation only.
how close the measurement is to the actual value. error exist in all measurements.
Systematic errors
a weakness of the instrument
the difference between reaction time of the brain and the action. zero error is when the pointer is not at zero when not in use.
Range of the measuring instrument – absolute error . Reaction time of the brain.
12 Absolute error : ……….………… ………. Zero error : ………...
Correct reading = observed reading – zero error
4.2 ……….. Occurs due to a) ……… b) ……… c) ……… Example :
a) Readings are close to the actual value but they are not consistent.
Can be minimized by consistently repeating the measurement at different places in an identical manner.
Parallax error :
Example :
Zero error of screw meter gauge Positive zero error
Horizontal reference
Horizontal
reference 3 divisions above
horizontal reference 2 divisions below
horizontal reference
Zero error = - 0.02 mm
Refer to the smallest reading that can be measured by an instrument. If, the smallest reading = 0.1 cm
Then, Absolute error = 0.1 / 2 = 0.05 cm
where the pointer is not at zero when not in used
+0.03 cm - 0.04 cm Positive zero error Negative zero error
Random error
carelessness in making the measurement.
parallex error , incorrect positioning of the eye when taking the readings. sudden change of ambient factors such as temperature or air circulation.
It occurs because the position of the eye is not perpendicular to the scale of the instrument wrong
right position of the eye (no error) wrong
Positive zero error Zero error = +0.03 Zero error = 0 1 cm 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 Zero error = 0 1 cm
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1.5 SCIENCETIFIC INVESTIGATION
Steps Explanation
1 Making
observation
Gather all available information about the object or phenomenon to be studied.
Using the five senses, sight, hearing, touch, taste and smell.
2 Drawing
inferences
A conclusion from an observation or phenomena using information that already exist.
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Identifying and controlling
variables
Variables are factors or physical quantities which change in the course of a scientific investigation.
There are three variables : i. Manipulated variables
- physical quantity which change according to the aim
of the experiment. ii. Responding variables
- physical quantity which is the result of the changed
by manipulated variable. iii. Fixed variables
physical quantities which are kept constant during the experiment.
4 Formulating a hypothesis
Statement of relationship between the manipulated variable and the responding variable those we would expect.
Hypothesis can either be true or false.
5 Conducting experiments
i. Conduct an experiment includes the compilation and interpretation of data.
ii. Making a conclusion regarding the validity of the hypothesis.
Plan and report an experiment
Situation : A few children are playing on a different length of swing in a playground. It is found that the time of oscillation for each swing is different.
Steps Example : refer to the situation above
1 Inference 2 Hypothesis
3 Aim
The period of the oscillation depends on the length of the pendulum.
When the length of the pendulum increases, the period of the oscillation increases.
Investigate the relationship between length and period of a simple pendulum.
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4 Variables Manipulated variable : the length of the pendulum. Responding variable : Period
Fixed variable : the mass of the pendulum and the displacement.
5 List of
apparatus and materials
Retort stand with clamp, 100 cm of thread, bob, meter rule, 2 blocks of clamp wood, protractor and stop watch. 6 Arrangement of the apparatus 7 Procedures 8 Tabulate the data
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1. Set up the apparatus as shown in the figure above.
2. Measure the length of the pendulum,l = 60.0 cm by using a meter rule.
3. Give the pendulum bob a small displacement 300.Time of 10 oscillations is measured by using a stop watch.
4. Repeat the timing for another 10 oscillations. Calculate the average time.
Period = t10 oscillations
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5. Repeat steps 2, 3 and 4 using l = 50.0 cm, 40.0 cm, 30.0 cm and 20.0 cm 1 1..5588 1 1..5500 1 1..3311 1 1..1199 0 0..9999 1 155..88 1 155..00 1 133..11 1 111..99 9 9..99 1 155..77 1 155..00 1 133..11 1 111..99 9 9..99 1 155..88 1 155..00 1 133..11 1 111..99 9 9..99 6 600..00 5 500..00 4 400..00 3 300..00 2 200..00 P Peerriioodd//ss ( (TT==tt1100//1100)) A Avveerraaggee 2 2 1 1 L Leennggtthh,,ll// c cmm
Time for 10 oscillations / s
Retort stand protractor
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15 9 10 11 Analyse the data Discussion Conclusion Reinforcement Chapter 1
Part A :Objective Question
1. Which of the following is a base SI quantity?
A Weight B Energy C Velocity D Mass
2. Which of the following is a derived quantity?
A Length B Mass C Temperature D Voltage
3. Which of the following is not a basic unit?
A Newton B kilogram C ampere D second
4. Which of the following quantities cannot be derived?
A Electric current B Power
C Momentum D Force
5. Which of the following quantities is not derived from the basic physical quantity of length?
A Electric charge B Density C Velocity D Volume T / s 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Graf of period, T vs pendulum’s length, l 0 10 20 30 40 50 60 l / cm Precautions :
1. Oscillation time is measured when the pendulum attained a steady state.
2. Time for 10 oscillations is repeated twice to increase accuracy. 3. Discussion (refer to given questions)
The period increases when the length of the pendulum increases. Hypothesis accepted.
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6. Initial velocity u, final velocity v, time t and another physical quantity k is related by the equation v - u = kt. The unit for k is
A m s-1 B m-1 s
C m s-2 D m2 s-2
7. Which of the following has the smallest magnitude? A megametre B centimetre C kilometre D mikrometre 8. 4 328 000 000 mm in standard form is A 4.328 x 10-9 m B 4.328 x 10-6 m C 4.328 x 106 m D 4.328 x 109 m 9. Which of the following measurements
is the longest?
A 1.2 x 10-5 cm B 120 x 10-4 dm
C 0.12 mm D 1.2 x 10-11 km
10. The diameter of a particle is 250 m. What is its diameter in cm?
A 2.5 x 10-2 B 2.5 x 10-4 C 2.5 x 10-6 D 2.5 x 10-8
11. Which of the following prefixes is arranged in ascending order? A mili, senti, mikro, desi B mikro, mili, senti, desi
C mili, mikro, desi, senti D desi, mikro, mili, senti
12. Velocity, density, force and energy are A basic quantities
B scalar quantities
C derived quantities D vector quantities
13. Which of the following shows the correct conversion of units? A 24 mm3 =2.4 x 10-6 m3
B 300 mm3=3.0 x 10-7 m3
C 800 mm3=8.0 x 10-2 m3 D 1 000 mm3=1.0 x 10-4 m3
14. Which of the following measurements is the shortest ?
A 3.45 x 103 m
B 3.45 x 104 cm
C 3.45 x 107 mm D 3.45 x 1012m
15. The Hitz FM channel broadcasts radio waves at a frequency of 92.8 MHz in the north region. What is the frequency of the radio wave in Hz?
A 9.28 x 104 B 9.28 x 105
C 9.28 x 107 D 9.28 x 1010 16. An object moves along a straight line
for time, t. The length of the line, s is given by the equation 2
2 1 gt s . The SI unit of g is A m2 s2 B m s-2 C s-1 D s-2 m
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Part B : Structure Question
1. A car moves with an average speed of 75 km h-1 from town P to town Q in 2 hours as shown in Figure 1. By using this information, you may calculate the distance between the two towns.
P Q
Figure 1
(a) (i) Based on the statements given, state two basic quantities and their respective SI units.
……… (ii) State a derived quantity and its SI unit.
……… (b) Convert the value 1 . m to standard form.
5 x 10-3
(c) Complete Table 1 by writing the value of each given prefix.
Table 1
(d) Power is defined as the rate of change of work done. Derive the unit for power in terms of its basic units.
(e) Calculate the volume of a wooden block with dimension of 7 cm, 5 cm breadth and 12 cm height in m3 and convert its value in standard form.
Distance : m and time : s Speed – m s-1 = 0.2 x 103 m = 2.0 x 102 m 10-9 10-6 106 109 Power = time work = time nt displaceme Force Unit = s m kgms2 = kg m2 s-3 Volume = (7 x 10-2) (5 x 10-2) (12 x 10-2) = 420 x 10-6 = 4.20 x 10-4 m3
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2. Figure 2 shows an ammeter of 0—3 A range.
Figure 2
(a) (i) Name component X. ………...
(ii) What is the function of X? ………. (b) Table 2 shows three current readings obtained by three students.
Table 2
(i) Did all the students use the ammeter in Figure2? ..………. (ii) Explain your answer in (b)(i).
……… 3. Figure 3 shows the meniscus of water in a measuring cylinder K, L, and M are three eye
positions while measuring the volume of the water.
(a) (i) Which of the eye positions is correct while taking the reading of the volume of water?
…….………
Figure 3
(b) The water in the measuring cylinder is replaced with 30 cm3 of mercury.
(i) In Figure 4, draw the meniscus of the
mercury in the measuring cylinder. Figure 4
(ii) Explain why the shape of the meniscus of mercury is as drawn in (b)(i).
………
No
3rd readings obtained by student 2 and 3 are out of the meter range.
L
The cohesive force is larger than the adhesive force
Mirror
