Definitions/Laws/Principles
AS LEVEL PHYSICS 9702
Physical quantities, units and, measurements
1
Systematic
error
2
Random error
3
Precision
4
5
6
Accuracy
Scalar
Vector
An error in readings which causes the reading to be
always larger or smaller than (or varying from) the true
reading by a constant amount.
an error in reading which causes the readings to be
scattered above or below the true value and is also not
constant.
the size of the smallest division (on the measuring
instrument). OR. It is determined by the range the
measurements/values/readings/data/results.
how close the reading is to the true value.
A physical quantity that has magnitude but no direction.
A physical quantity which has both magnitude and
direction.
Kinematics
1
2
3
4
Displacement
Speed
Velocity
Acceleration
distance in a specified direction (from a point).
distance travelled per unit time.
The rate of change of the displacement of an object.
The rate of change of an object’s velocity.
Dynamics
1
Mass
2
Linear
Momentum
Force
Newton
3
4
it is the property of an object which resists change in motion.
OR
A measure of the amount of matter within an object.
The product of an object’s mass and its velocity.
Rate of change of momentum.
The force that will give a 1 kg mass an acceleration of 1 m
s−2 in the direction of the force. 1 N = 1 kg m s −2.
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6
7
8
9
10
Newton's 1st
law
Newton's 2nd
law
An object will remain at rest or keep travelling at constant
velocity unless it is acted on by a resultant force.
The resultant force acting on an object is equal to the rate
of change of its momentum. The resultant force and the
change in momentum are in the same direction.
OR
For an object of constant mass, the acceleration is
proportional to the resultant force acting on it. The
direction of resultant acceleration is the same as resultant
force.
When two bodies interact, the forces they exert on each
other are equal and opposite.
In a closed system, when bodies interact, the total
momentum in any specified direction remains constant.
Newton's 3rd
law
Principle of
conservation of
linear
momentum
Perfectly Elastic A collision is perfectly elastic when kinetic energy is
collision
conserved. Momentum and total energy are always
conserved.
Inelastic
A collision is inelastic when kinetic energy is not
collision
conserved; some is transferred to other forms such as
heat.
Forces, density and pressure
1
2
Centre of
gravity
Moment
3
Principle of
moments
4
Conditions of
equilibrium
5
6
Density
Pressure
The point where the entire weight of an object appears to
act.
The moment of a force about a point is the magnitude of
the force, multiplied by the perpendicular distance of the
point from the line of the force.
For an object in (rotational) equilibrium, the sum of
clockwise moments about a point is equal to the sum of
anticlockwise moments about the same point.
1) The resultant force in any direction must be zero.
2) The resultant torque in any direction (about any point)
must be zero.
The mass per unit volume of a material.
The force acting normally per unit area of a surface.
Deformation
1
2
3
4
5
6
7
8
Elastic limit
The value of stress (or force) beyond which an object will
not return to its original dimensions if the stress (or force)
is removed.
Limit of
The value of stress (or force) beyond which the force and
proportionality extension (or compression) of an object are no longer
proportional to each other.
Hooke's law
The extension/compression produced in an object is
proportional to the force producing it, provided that limit
of proportionality is not exceeded.
Spring constant The ratio of force to extension for a spring or a wire.
Stress
The force acting per unit cross-sectional area (force/cross
sectional area).
Strain
The extension per unit original length produced by tensile
or compressive forces (extension/original length).
Young modulus The ratio of stress to strain for a given material, resulting
from tensile forces, provided Hooke’s law is obeyed.
Strain energy
the energy stored (in an object) due to extension /
or elastic
compression / change of shape.
potential
energy
Work, energy and power
1
Work
2
Energy
3
Power
4
Efficiency
5
Gravitational
potential
energy
Kinetic energy
6
The product of the force and the distance moved in the
direction of the force.
A calculated quantity which is conserved during any change;
that which is transferred when a force does work. (Ability to
do work.)
The rate at which energy is transferred or the rate at which
work is done.
The ratio of useful output energy to the total input energy
for a device, expressed as a percentage.
the energy/ability to do work of a mass that it has or is
stored due to its position/height in a gravitational field.
the energy/ability to do work an object has due to its
motion.
7
Principle of
conservation
of energy
The idea that, within a closed system, the total amount of
energy in all its forms is unchanged during any change.
Waves
1
2
3
4
Transverse
wave
Longitudinal
wave
Progressive
wave
Stationary or
standing wave
A wave in which the displacement of particles is
perpendicular to direction of energy propagation.
A wave in which the displacement of particles is parallel to
direction of energy propagation.
A wave that carries energy from one place to another
without the transfer of the medium/material.
A wave pattern produced when two progressive waves of
the same frequency travelling in opposite directions
combine. It is characterised by nodes and antinodes. Energy
is trapped in a stationary wave, unlike progressive waves.
distance (in a specified direction of particle/point on wave)
from the equilibrium position.
maximum displacement (of particle / point on wave).
The number of oscillations (performed by a point on the
wave) per unit time.
OR
The number of wavefronts passing a point per unit time.
time for one oscillation/one vibration/one cycle.
OR
time between adjacent wavefronts/points in phase.
OR
shortest time between two wavefronts/points in phase.
distance moved by wavefront / energy during one cycle /
vibration / oscillation / period (of source) OR minimum
distance between two wavefronts/points in phase OR
distance between two adjacent wavefronts/points in phase.
The change in frequency or wavelength of a wave observed
when the source of the wave is moving towards or away
from the observer (or the observer is moving relative to the
source).
When the vibrations of a transverse wave are in all planes.
5
Displacement
6
7
Amplitude
Frequency
8
Period
9
Wavelength
10
Doppler effect
11
Unpolarised
wave
Plane
When the vibrations of a transverse wave are in one plane
polarised wave only.
Malul’s law
When a polarised wave is passed through a polarisation
filter:
12
13
𝐼 = 𝐼0 cos2 (𝜃)
Where;
I = final intensity
I0 = initial intensity
𝜃 = angle between the transmission axis of the polarisation
filter and the axis of the polarised wave
Superposition
1
Principle of
superposition
2
Interference
3
Diffraction
4
Coherence
5
Conditions for
formation of a
stationary
wave
Nodes
Antinodes
6
7
When two waves meet at a point, the resultant
displacement of the wave produced is equal to the sum
of their individual displacements.
the sum/addition/combination of the displacements of
overlapping/meeting waves
The spreading of a wave when it passes through a gap or
past the edge of an object.
Two sources are coherent when they emit waves with a
constant phase difference between them.
(1) (two) waves (travelling at same speed) in opposite
directions overlap, (2) (waves are same type and) have
same frequency / wavelength
A point on a stationary wave with zero amplitude.
A point on a stationary wave with maximum amplitude.
Current of electricity
1
2
Current
Ampere
3
4
Coulomb
Number
density of
charge carriers
Mean Drift
velocity
Electromotive
force (emf)
5
6
Rate of flow of charge.
1 Ampere is the amount of current when 1 Coulomb of
charge passes a point in 1 second.
Ampere second.
The number of particles, such as free electrons, per unit
volume in a material.
The average speed of a collection of charged particles
when a current is flowing.
work done or energy transformed (from other forms to
electrical) when unit charge is moved round a complete
circuit.
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8
9
10
11
Potential
difference
(p.d)
Volt
Resistance
Ohm
Ohm’s law
work done or energy transformed (from electrical to other
forms) per unit charge.
Joules per Coulomb.
The ratio of potential difference to current.
Volts per Ampere.
The current in a metallic conductor is directly proportional
to the potential difference across its ends, provided its
temperature remains constant.
D.C. circuits
1
2
Kirchhoff's 1st The sum of the currents entering any point (or junction) in a
law
circuit is equal to the sum of the currents leaving that same
point. This law represents the conservation of charge.
Kirchhoff's
The sum of the e.m.f.s round a closed loop in a circuit is
2nd law
equal to the sum of the p.d.s in that same loop. This law
represents the conservation of energy.
Particle physics
1
Isotopes
2
Antimatter
3
Fundamental
particles
Hadrons
Baryons
Mesons
Leptons
4
5
6
7
Nuclei of the same element with a different number of
neutrons but the same number of protons.
An antiparticle has the same mass as a matter particle but
equal and opposite charge. When a particle and its
antiparticle interact, they annihilate each other and their
mass coverts into pure energy.
a particle that is not made up of any other particles.
Any particle which is affected by the strong nuclear force.
Hadrons that are made up of 3 quarks.
Hadrons that are made of 1 quark and 1 antiquark.
Any particle which is not affected by the strong nuclear
force.