Kinetic Model Of Matter: Brownian Motion is the movement of smoke particles in a random and continuous motion in all direction.
Conclusion: Provide Evidence that air molecules are always in continuous and random motion.
Temperature:
It is the measure of the degree of hotness of a body. Heat refers to the amount of thermal energy that is contained in a body.
Lower-fixed point aka Ice Point:
Temperature of pure melting ice at standard atmospheric pressure. Upper-fixed point aka steam point:
Temperature of steam from boiling water at standard atmospheric pressure.
Transfer of Thermal Energy: Conduction is the process by which heat is transferred through a medium by the collisions of one particle to another.
Convection is the process by which heat is transmitted from one place to another by the movement of heated particles in a gas or liquid. Radiation is the process of heat transfer through the emission or absorption of electromagnetic waves Thermal Properties of Matter:
Energy = power x time Internal Energy is the sum of kinetic energy and potential energy of all the particles.
Heat Capacity(C) is the amount of heat required to raise the temperature of the object by 1oc
.
Specific heat capacity(c): Is the amount of heat required to raise the temperature of 1kg of the object by 1oc
Melting is the process in which a substance changes from a solid state to a liquid state without a change in temperature.
Boiling is the process in which a substance changes from a liquid state to a gaseous state without a change in temperature. Latent heat of fusion (lf) of a substance is the quantity of heat needed to change a unit mass of the substance from solid to liquid without a change in temperature
.
Latent heat of vaporization (lv): of a substance is the quantity of heat needed to change a unit mass of the substance from liquid to gas without a change in temperature.
Light:
Law 1: The angle of incidence is = to the angle of reflection.
Law2: The incident ray, reflected ray and normal lies at the point of incidence all lie on the same plane. Refraction: The bending of light when it passes from one transparent medium to another.
Law1: The incident ray, refracted ray and normal the point of incidence all lie on the same plane
Law2: For 2 given media,
Q
C
θ
=
Q
=
mc
θ
fQ ml
=
vQ ml
=
sin
sin
i
n
r
=
(Less dense to denser medium)sin
sin
r
n
i
=
(Denser to less dense medium) (n= refractive index or optical density)Refractive index of medium:
C= speed of light 3x108 V= velocity of light Total internal reflection: Critical angle(c): is the angle of incidence for which the angle of refraction in the optically dense medium is 90o.
Conditions for TIR:
1. Light must travel from an optically denser medium into optically less dense medium
2. Angle of incidence (i) must be greater than the critical angle(c).
Thin converging lenses: Focal length F is the distance between the optical center of the lens to the focal point
Linear magnification (m) is the ratio of the image height (hi) to the object height (ho).
(Or the image distance (v) from the lens to the object distance (u) from the lens)
General Wave Properties: Wave: Phenomenon which energy is transferred through vibrations.
Amplitude (a): Maximum displacement of wave from rest position. Wavelength (
λ
)
: distance between 2 identical points on successive waves. Frequency (f): no of complete wave in one second.Period (T): time taken to generate one complete wave.
Speed of wave: Distance moved by any point on the wave in one second.
Transverse wave: are waves in which the direction of vibration is perpendicular to the direction of wave motion.
Longitudinal waves: are waves in which the direction of vibration of the wave particles is parallel to the direction of wave motion.
Wave front: imaginary line on a wave that joins all points which have the same phase of vibration. Sound:
Compressions: region where air particles is slightly higher than normal atmospheric pressure.
Rarefaction: region where air particles is slightly lower than normal atmospheric pressure.
Echo: reflected sound wave from large and hard surface.
Loudness: dependent on amplitude.
Pitch: dependent on frequency of the wave
c
n
v
=
1
sin c
n
=
i oh
m
h
=
v
m
u
=
1
T
f
=
Hence,v
=
f
λ
Ultrasound are sound that are above the upper hearing limit of the human ear. Kinematics: Scalar: units magnitude no direction Vector: direction units no magnitude
Distance (d) total length covered by a moving object. Displacement(s) the distance measured in a specific direction.
Speed is the rate of change of distance with time.
Velocity (v) is the rate of change of displacement with time.
Acceleration (a) is the rate of change of velocity with time.
Terminal Velocity: When an object falls at a constant maximum velocity, with an acceleration of 0m/s2, it is known as terminal velocity.
The Downward force is equal to the upward force, hence no net force. Distance-time graph: Gradient: speed of object. If it is a straight line, it is travelling at a constant speed. Velocity-time/ speed-time graph:
Gradient gives the acceleration. Positive gradient: acceleration. Negative gradient: Deceleration or retardation. Zero gradient: (i) object at rest (ii) moving at
constant speed Area under graph equals to distance travelled.
In general, average speed is always area under graph divide by time. Average speed= When acceleration is constant in graph, v= Final velocity u=Initial velocity
t= time taken for change
Dynamics:
Newton 1st Law:
When there is no net force acting on a body, the body will remain at rest and a body in motion will continue its motion at constant velocity.
Newton 2nd Law:
Net force action on a body is directly proportional to the product of the object’s mass and the acceleration it produces.
Resultant/net force:
Resultant force produces acceleration
constant net
force=constant acceleration. doubling net force will double acceleration produce Doubling mass requires a force twice as large to achieve the same acceleration.
d
Speed
t
=
s
Velocity
t
=
v u
a
t
−
=
.
.
area under graph
t
1
.
(
)
2
average speed
=
v u
+
F
R=ma
Newton 3rd Law:
For every action, there is an equal and opposite reaction, and they act on different bodies.
Inertia is the reluctance of a body to change its state of rest or motion. Or
It is the tendency of a body to remain at rest, or continue moving at a constant speed.
Friction is a force that opposes motion.
Mass, Weight & Density: Mass is a measure of the amount of matter in an object. SI unit: kilogram (kg) Weight is due to the pull of gravity (or, gravitational force of attraction) upon a mass.
Gravitational field strength (g) is define as the gravitational force acting per unit mass of a body.
Density is the mass per unit volume of a substance.
M
V
ρ
=
Turning Effect of Forces Moment of force is the product of the force, and the perpendicular distance from the line of action of the force to the pivot.
Moment
=
Fx
⊥
d
Principle of moments states that when a body is in equilibrium, the total clockwise moments about the pivot = to the total anti-clockwise moment about the same pivot.
Centre of gravity of an object is the point where the whole weight of the object seems to act on. Stability is a measure of a body’s ability to regain its original position
Work, Energy & Power: Work done by a force is the product of force applied and the distance moved in the direction of the force.
.
W D
=
F x d
Energy is defined as the capacity to do work.
K.E is the energy possesses due to its motion.
2
1
. .
2
K E
=
mv
G.P.E is the energy a body possesses due to its
position from the surface of the earth.
. . .
G P E
=
mgh
The principle of the conservation of energy states that Energy can neither be created nor destroyed in any process. It can be converted from one form to another or
transferred from one body to another but the total amount remains constant.
Power is the rate of work done or energy converted.
.
W D
P
t
=
orP
E
t
=
Pressure is the force acting per unit area on a body.
F
P
A
=
Pressure due to liquid:
P
=
h g
ρ
Atmospheric pressure is the weight exerted by the atmosphere.
Output force in a hydraulic system= B B A A
A
F
F
A
=
A barometer is an instrument used for measuring atmospheric pressure.Static Electricity
Electric Field is the region where an electric charge experiences an electric force. Magnetism
Magnetic Field is the region around a magnet in which a magnetic force can be detected by a magnetic material.
Electricity
Charge is measured in coulombs (C)
Charge of one electron is -1.6x1018 .
Current is the rate of flow of charge that flows through any particular point.
Q
I
t
=
E.m.f is defined as the work done by a force in driving a unit charge around a complete circuit.
W
Q
ε
=
Voltage is the work done to drive a unit charge through the component.
W
V
Q
=
Resistance is the ratio of the potential difference across the component to the current flowing though it.
RI
=
V
Power of an electrical component is the product of the current flowing through it and the potentialdifference across it.
P
=
IV
Ohm’s Law states that the current passing through a conductor is directly
proportional to the potential difference between its ends provided that the physical conditions and temperature remains constant.
Diode only allows current to flow in one direction Rectification is the process of converting alternating current to a direct current usually through the use of a diode.
Potential Divider divides voltage proportionally into 2 voltages. 2 2 1 2
(
)
TV
IR
V
=
I R
+
R
Earth Wire is used for safety reasons. Connected to metal casing of an appliance and direct excess currents due to the ground when there is a leakage or a short circuit.
Fuse melts when excess current flows through it breaking the circuit to prevent current from
flowing to prevent user from electrocution and also prevent damage to appliance.
Electromagnetism/
Electromagnetic Induction Permanent Magnet: provide strong magnetic field.
Curved in to provide radial field.
Carbon Brushes: Provide electrical contact between circuit and coil
Soft Iron Core: to
concentrate magnetic field lines around the coil to exert a greater force on the coil.
(D.C motor)Split ring commutator: Reverses the direction of current flowing into the coil for every half a turn to ensure the coil rotates in one direction. (A.C motor)Slip ring: Reverse direction of induced current flowing in the coil for every half a rotation. Why transformer need A.C?
It is to provide a constantly changing magnetic field for electromagnetic induction. Hence a constantly
