Physics
01 Physical Quantities, Units and Measurement
02 Kinematics
03 Dynamics
04 Mass, Weight and Density
05 Turning Effect of Forces
06 Pressure
07 Energy, Work and Power
08 Kinetic Model of Matter
09 Transfer of Thermal Energy
10 Temperature
11 Thermal Properties of Matter
12 General Wave Properties
Seven Basic Physical Quantities
Time (s)
- Mass (kg)
- Temperature (K)
- Electric current (A)
- Amount of substance (mol)
- Luminous intensity (cd)
Length (m)
Instrument
Vernier Callipers
Micrometer Screw Gauge
Metre Ruler
Tape Measure
1mm
1mm
0.1mm
0.01mm
Can be measured using
- Pendulums
- Clocks
- Stopwatches
Periodic motions called oscillations
Scalar Quantities
Vector Quantities
Magnitude
Distance (m)
Speed (m/s)
Speed = Distance / Time
Average Speed = Total Distance / Total time
Magnitude + Direction
Displacement (m)
Velocity (m s^-1)
Acceleration (m s^-2)
Area under Velocity Time graph is displacement
Velocity = displacement/time
Gradient of D/T graph is velocity
Acceleration due to gravity approx 10m/s^2
when resistive forces are equivalent to acceleration due to gravity during free fall, since net force is 0 terminal velocity is reached
Forces (N)
Newtons laws
Newton's 2nd Law
Newton's 3rd Law
Newton's 1st Law
For every action in nature there is an equal and opposite reaction (Action-Reaction pairs)
An object at rest will remain at rest, an object in motion will stay in motion at constant speed in in a straight line in the absence of resultant force acting on it.
F = ma (Force = Mass x Acceleration)
Contact Forces
Non-Contact Forces
Friction
Normal Reaction Force
Tension
Gravitational Force
Electric Force
Magnetic Force
Mass (kg)
- Amount of substance in a body
- Inertia
Is related to
Weight (N)
Density (kg m^-3)
Mass per unit volume
The gravitational force acting upon the object
Gravitational field strength:
Definition: Region where a mass experiences a force due to gravitational attraction
Unit: Gravitational field strength (g) is measured in newtons per kilogram (N/kg).
W = m x g (Weight = mass x gravitational field(On Earth is 10N/kg))
P = m / v (Pressure = mass divided by volume)
Moment of a force (N m)
Turning Effect of a Force
Moment = Force x Perpendicular Distance
Clockwise
Anticlockwise
Principle of Moments
Sum of clockwise moments about a pivot = Sum of anticlockwise moments about the same pivot
Stability of an object
Centre of gravity
Base Area
Pressure (Pa)
Pressure in gases
Pressure in liquids
Atmospheric Pressure
Is defined as Force acting per unit area
p = F/A(Pressure over Area)
where
p = pressure (Pa or N m^-2)
F = force (N)
A = area (m2)
Manometer
Mercury Barometer
Measuring the height of the mercury column above the surface of the mercury in the trough
Pressure difference
Measuring the height difference between liquid columns
Transmitted equally throughout an enclosed liquid
Pressure p = hpg
where
h = height of liquid column (m)
p = density of liquid (kg m^-3)
g= gravitational field strength (N kg^-1)
applied in Hydraulic machines
for example
Hydraulic press
Car hydraulic disc
brake system
Energy (J)
is the capacity to do Work (J)
The Principle of Conservation of Energy
Energy cannot be created or destroyed, but can be converted from one form to another. Types of energy are
Kinetic Energy (0.5mv^2)
Potential Energy
Nuclear Energy
Gravitational Potential Energy (mgh(mass x gravitational field x height))
Thermal Energy
Chemical Potential Energy
Electrical Energy
Elastic Potential Energy
Light Energy
Efficiency can be equated as
Efficiency = useful energy output / total energy output * 100%
Related to Power
Matter is made of tiny particles (atoms or molecules) that are in continuous, random motion.
explains the properties of
Brownian motion
Increase in temperature results in particles having higher kinetic energy (i.e. particles move faster).
Solid
Liquid
Gas (No Fixed shape, No Fixed volume, Compressible, Low Density)
Gas Pressure is due to the collision of gas particles with the walls of the container.
is directly proportional to Temperature
is directly proportional to Volume
Is inversely Proportional to Volume
Shape: Fixed shape
Volume: Fixed volume
Compressibility: Incompressible
Density: High Density
Intermolecular force(IMF): Very strong
Separation of particles: Very close together
Arrangement: Regular
Motion: Vibrate about fixed positions
Shape: No Fixed shape
Volume: Fixed volume
Compressibility: Incompressible
Density: High Density
Intermolecular force(IMF): Strong
Separation of particles: Close together
Arrangement: Irregular
Motion: Slide over one another
Shape: No Fixed shape
Volume: No Fixed volume
Compressibility: Compressible
Density: Low Density
Intermolecular force(IMF): Very weak
Separation of particles: Far apart
Arrangement: Irregular
Motion: Move in all directions
The greater the temperature, the greater the motion of molecules (Temperature increase, kinetic energy increase, force per collision increase, frequency per collision increase, pressure increase)
A change in pressure of a fixed mass of gas at constant volume is caused by a change in temperature of the gas / A change in volume occupied by a fixed mass of gas at constant pressure is caused by a change in the temperature of the gas / a change in pressure of a fixed mass of gas at constant temperature is caused by a change in volume of the gas
Temperature increase, kinetic energy increase, force per collision increase, frequency per collision increase, pressure increase
volume of container increase, number of gas particles per unit volume decrease, frequency of gas particles colliding decrease, pressure decrease
Temperature increase, kinetic energy increase, force per collision increase, volume of container increase, number of gas particles per unit volume decrease, frequency of gas particles colliding with the inner walls of the container decrease, pressure remains constant
(a) Gas particles move about randomly, continuously and in all directions
(b) They collide with the inner walls of the container and exert a force on them.
(c) The average force exerted per unit area is the gas pressure.
(d) The frequency of collisions also affect the overall gas pressure exerted.
infer from a Brownian motion experiment the evidence for the movement of particles
Particles like dust move in continuous random motion under observation
The dust particles are suspended within a medium, where the air molecules cannot be seen by the naked eye. The collision of the dust particle and the molecules of the medium is what is inferred to be why the dust particle move continuously and randomly
since these particles like dust are suspended within a medium like air, it can be inferred that are moving continuously and randomly, and collide with the dust particle
Conduction
Convection
Radiation
Introduction
The kinetic model of matter states that particles vibrate, translate (move from one location to another) and even rotate (evolve about an imaginary axis). These motions give the particles kinetic energy.
Temperature is a measure of the average amount of kinetic energy possessed by the particles in a sample of matter. The more the particles vibrate, translate and rotate, the greater the temperature of the object
Temperature
Temperature is a measure of the average amount of kinetic energy possessed by the particles in a sample of matter
Atomic/Molecular vibration
Free electron diffusion
Particles at the heated end gain kinetic energy and vibrate vigorously. They collide with neighbouring particles, causing them to vibrate more vigorously as well. This process continues until the particles at the cooler end are also set into vigorous vibration
In metals, thermal energy is also transferred through the process of electron diffusion
Electrons at the heated end gain kinetic energy and move more rapidly
They collide atoms in the cooler parts of the metal and transfer their kinetic energy in the process
This continues until the particles at the cooler end are also set into vigorous vibration
Radiation is the transfer of thermal energy in the form of electromagnetic waves (e.g. infrared radiation) without the aid of a medium (can travel through vacuum) All bodies emit infrared radiation. Infrared radiation does not require a medium to be transmitted.
Factors
Surface Area
Surface Temperature
Colour and Texture
Bright and Shiny surfaces are greater emitters of thermal radiation
Dark and Dull surfaces are poorer emitters of thermal radiation
A greater surface area results in a high rate of absorption or emission of thermal radiation
A higher temperature relative to its surrounding temperature results in a higher rate of emission of thermal radiation
A lower temperature relative to its surrounding temperature results in a higher rate of absorption of thermal radiation
When the water at the bottom of the flask is heated, it expands, becomes less dense than the surrounding water and rises. The upper region of water is cooler, denser, and sinks to the bottom of the flask. The process repeats and sets up a convection current due to the difference in the densities of water in the different regions.
Temperature (K)
Measured with thermometers
Thermometric Substances
Temperature Scales
Types of thermometers
Liquid-in-glass thermometer
Resistance thermometer
Thermocouple thermometer
Physical properties that vary continuously and linearly with temperature
Lower and upper fixed points e.g. ice point (0 C, steam point (100° C)
Celsius scale 
Thermometric properties
Mercury in glass thermometer / alcohol in glass thermometer
Thermocouple thermometer
Resistance Thermometer
Constant volume gas thermometer
Volume of a fixed mass of liquid
Electrical resistance of a piece of metal
Pressure of a fixed mass of gas at constant volume
Electrical voltage or electromotive force (e.m.f.)
Kelvin to Celsius
K = ºC + 273
Internal energy
Internal Potential Energy
Internal Kinetic Energy
as molecules vibrate/move around a substance motion is produced, and is relative to the temperature of the object → temperature is a measure of the average internal kinetic energy of its particles
comes from the intermolecular forces between particles in an object and is dependent on the strength of the intermolecular forces, and how far apart the particles are separated.
Heat Capacity
s the amount of thermal energy needed to increase the temperature of a substance by 1K or 1C° It uses the SI unit Joule per kelvin (J/K).
Q=CΔθ,
where Q = thermal energy absorbed or released by object (J)
C = Heat Capacity Δθ = Change in temperature (K or C°)
Specific Heat Capacity
is the amount of thermal energy needed to increase the temperature of a unit mass by 1K or 1C°. It uses the SI unit joule per kilogram per kelvin (J/(kg/K))
Q = mcΔθ,
where Q = thermal energy absorbed or released by object (J)
m = Mass of substance (kg)
c = Specific Heat Capacity (J/(kg/K))
Δθ = Change in temperature (K or C°)
Type of Waves
Transverse
Longitudinal
Sound Waves
Electromagnetic
Rope
Water
Ripple Tank
Used to demonstrate basic properties of waves.
Ripples are generated by a vibrating dipper.
Wavefront
A wavefront joins all points on a wave that are in the same phase, and is perpendicular to the direction of motion.
Parts of a wave
Crest
Troughs
Centre of Compressions
Centre of Rarefactions
Amplitude, A
Wavelength, λ
Phase
Period, T
Frequency, f
Highest point on Transverse Wave
Lowest point on Transverse Wave
Centre of region in Longitudinal Wave where Particles are Closest to each other.
Centre of region in Longitudinal Wave where Particles are Furthest Apart.
Maximum Displacement of a point from its rest position.
Shortest Distance between any 2 points in phase.
Points are in same phase if they have the same speed,
direction of travel and displacement from their rest position
Time Taken for a complete wave
Number of complete waves per unit time.
Formulas
Frequency
F = 1/T
Speed of wave
v = f λ
angle of incidence = angle of refraction
Travelling through medium
Deep water <-> shallow water
Water waves travel faster in deep than shallow water.
Frequency remains unchanged
Wavelength decreases
Wave bends towards normal