Important Equations in Physics for IGCSE course
General Physics:
1 For constant motion: ‘v’ is the velocity in m/s, ‘s’ is the
= distance or displacement in meters
and ‘t’ is the time in sec
2 For acceleration ‘a’ − u is the initial velocity, v is the final
=
velocity and t is the time
3 Graph: in velocity-time
graph the area under the Area of a rectangular shaped graph = base × height
graph is the total Area of triangular shaped graph = ½ × base × height
distance covered
4 Weight is the force of w is the weight in newton (N), m is
gravity and mass is the = × the mass in kg and g is acceleration
amount of matter due to gravity = 10 m/s2
3
5 Density ‘ρ’ in kg/m m is the mass and V is the volume
=
(ρ is the rhoo)
6 Force F in newtons (N) = × m is the mass and a is acceleration
7 Terminal Velocity: ℎ ( )= ( )
falling with air resistance implies no net force, therefore no acceleration, constant velocity
8 Hooke’s Law F is the force, x is the extension in
= ×
meters and k is the spring constant
9 Moment of a force in N.m = × d is the perpendicular distance from
(also turning effect) the pivot and F is the force
10 Law of moment or =
equilibrium => × = ×
11 Conditions of Equilibrium Net force on x-axis=zero, net force on y-axis= zero, net moment=zero
11 Work done W joules (J) = × F is the force and d is the distance
covered by an object same direction
12 Kinetic Energy Ek in 1 m is the mass(kg) and v is the
joules (J) = × × velocity (m/s)
2
13 Potential Energy ∆Ep in Δ = × × Δℎ m is mass (kg) and g is gravity and
joules (J) ∆h is the height from the ground
14 Law of conservation of =
energy: 1
× ×ℎ = × ×
2
15 Power in watts (W) Power is the rate of doing work or
= rate of transferring the energy from
one form to another
=
16 Efficiency:
= × 100
17 Pressure p in pascal (Pa) F is the force in newton (N) and A is
= the area in m2
18 Pressure p due to liquid ρ is the density in kg/m3, h is the
= × ×ℎ height or depth of liquid in meters
and g is the gravity
5
19 Atmospheric pressure P=760mmHg = 76cm Hg =1.01x10 Pa
20 Energy source renewable can be reused non-renewable cannot be reused
Hydroelectric eg dam, waterfall Chemical energy eg petrol, gas
Geothermal eg from earth’s rock Nuclear fission eg from uranium
Solar eg with solar cell
Wind energy eg wind power station
Tidal/wave energy eg tide in ocean
Prepared by Faisal Jaffer Revised on 21 June 2010 Page 1
, Thermal Physics:
1 Boyle’s law: Pressure and volume pV=constant p1 and p2 are the two pressures in Pa
are inversely proportional ∝ × = × and V1 and V2 are the two volumes in m3
2 Thermal Expansion (Linear) L = ×Lo ×
Lo is the original length in meters,
is the change in temperature in oC,
L is the change in length in meters (L1- Lo) and
is the linear expansivity of the material
3 Thermal Expansion (Cubical) Vo is the original volume in m3,
V = Vo
is the change in temperature in oC,V is
= 3 the change in volume in m3 (V1- Vo) and
is the cubical expansivity of the material.
4 Charle’s Law: V is the volume in m3 and T is the temperature
=
Volume is directly proportional to in kelvin (K).
absolute temperature
=
∝
5 Pressure Law: = p is the pressure in Pa and T is the
Pressure of gas is directly temperature in Kelvin (K).
proportional to the absolute =
temperature ∝
6 Gas Law (combining above laws) In thermal physics the symbol θ is used for
=
celsius scale and T is used for kelvin scale.
=
7 Specific Heat Capacity: c is the specific heat capacity in J/(kg oC),
Amount of heat energy required to = Q is the heat energy supplied in joules (J),
×∆
raise the temperature of 1 kg mass m is the mass in kg and Δθ is the change in
by 1oC. temperature
8 Thermal Capacity: amount of heat Thermal capacity=m×c The unit of thermal capacity is J/oC.
require to raise the temperature of
a substance of any mass by 1oC ℎ =
∆
9 Specific latent heat of fusion Lf is the specific latent heat of fusion in J/kg or J/g,
=
(from solid to liquid) Q is the total heat in joules (J),
m is the mass of liquid change from solid in kg or g.
10 Specific latent heat of vaporization Lv is the specific latent heat of vaporization in J/kg or
=
(from liquid to vapour) J/g, Q is the total heat in joules (J), m is the mass of
vapour change from liquid in kg or g.
11 Thermal or heat transfer In solid = conduction
In liquid and gas = convection and also convection current
(hot matter goes up and cold matter comes down)
In vacuum = radiation
12 Emitters and Radiators Dull black surface = good emitter, good radiator, bad reflector
Bright shiny surface = poor emitter, poor radiator, good reflector
13 Another name for heat radiation Infrared radiation or radiant heat
14 Melting point Change solid into liquid, energy weaken the molecular bond, no
change in temperature, molecules move around each other
15 Boiling point Change liquid into gas, energy break molecular bond and
molecules escape the liquid, average kinetic energy increase, no
change in temperature, molecule are free to move
16 Condensation Change gas to liquid, energy release, bonds become stronger
17 Solidification Change liquid to solid, energy release bonds become very strong
18 Evaporation Change liquid to gas at any temperature, temperature of liquid
decreases, happens only at the surface
Prepared by Faisal Jaffer Revised on 21 June 2010 Page 2
General Physics:
1 For constant motion: ‘v’ is the velocity in m/s, ‘s’ is the
= distance or displacement in meters
and ‘t’ is the time in sec
2 For acceleration ‘a’ − u is the initial velocity, v is the final
=
velocity and t is the time
3 Graph: in velocity-time
graph the area under the Area of a rectangular shaped graph = base × height
graph is the total Area of triangular shaped graph = ½ × base × height
distance covered
4 Weight is the force of w is the weight in newton (N), m is
gravity and mass is the = × the mass in kg and g is acceleration
amount of matter due to gravity = 10 m/s2
3
5 Density ‘ρ’ in kg/m m is the mass and V is the volume
=
(ρ is the rhoo)
6 Force F in newtons (N) = × m is the mass and a is acceleration
7 Terminal Velocity: ℎ ( )= ( )
falling with air resistance implies no net force, therefore no acceleration, constant velocity
8 Hooke’s Law F is the force, x is the extension in
= ×
meters and k is the spring constant
9 Moment of a force in N.m = × d is the perpendicular distance from
(also turning effect) the pivot and F is the force
10 Law of moment or =
equilibrium => × = ×
11 Conditions of Equilibrium Net force on x-axis=zero, net force on y-axis= zero, net moment=zero
11 Work done W joules (J) = × F is the force and d is the distance
covered by an object same direction
12 Kinetic Energy Ek in 1 m is the mass(kg) and v is the
joules (J) = × × velocity (m/s)
2
13 Potential Energy ∆Ep in Δ = × × Δℎ m is mass (kg) and g is gravity and
joules (J) ∆h is the height from the ground
14 Law of conservation of =
energy: 1
× ×ℎ = × ×
2
15 Power in watts (W) Power is the rate of doing work or
= rate of transferring the energy from
one form to another
=
16 Efficiency:
= × 100
17 Pressure p in pascal (Pa) F is the force in newton (N) and A is
= the area in m2
18 Pressure p due to liquid ρ is the density in kg/m3, h is the
= × ×ℎ height or depth of liquid in meters
and g is the gravity
5
19 Atmospheric pressure P=760mmHg = 76cm Hg =1.01x10 Pa
20 Energy source renewable can be reused non-renewable cannot be reused
Hydroelectric eg dam, waterfall Chemical energy eg petrol, gas
Geothermal eg from earth’s rock Nuclear fission eg from uranium
Solar eg with solar cell
Wind energy eg wind power station
Tidal/wave energy eg tide in ocean
Prepared by Faisal Jaffer Revised on 21 June 2010 Page 1
, Thermal Physics:
1 Boyle’s law: Pressure and volume pV=constant p1 and p2 are the two pressures in Pa
are inversely proportional ∝ × = × and V1 and V2 are the two volumes in m3
2 Thermal Expansion (Linear) L = ×Lo ×
Lo is the original length in meters,
is the change in temperature in oC,
L is the change in length in meters (L1- Lo) and
is the linear expansivity of the material
3 Thermal Expansion (Cubical) Vo is the original volume in m3,
V = Vo
is the change in temperature in oC,V is
= 3 the change in volume in m3 (V1- Vo) and
is the cubical expansivity of the material.
4 Charle’s Law: V is the volume in m3 and T is the temperature
=
Volume is directly proportional to in kelvin (K).
absolute temperature
=
∝
5 Pressure Law: = p is the pressure in Pa and T is the
Pressure of gas is directly temperature in Kelvin (K).
proportional to the absolute =
temperature ∝
6 Gas Law (combining above laws) In thermal physics the symbol θ is used for
=
celsius scale and T is used for kelvin scale.
=
7 Specific Heat Capacity: c is the specific heat capacity in J/(kg oC),
Amount of heat energy required to = Q is the heat energy supplied in joules (J),
×∆
raise the temperature of 1 kg mass m is the mass in kg and Δθ is the change in
by 1oC. temperature
8 Thermal Capacity: amount of heat Thermal capacity=m×c The unit of thermal capacity is J/oC.
require to raise the temperature of
a substance of any mass by 1oC ℎ =
∆
9 Specific latent heat of fusion Lf is the specific latent heat of fusion in J/kg or J/g,
=
(from solid to liquid) Q is the total heat in joules (J),
m is the mass of liquid change from solid in kg or g.
10 Specific latent heat of vaporization Lv is the specific latent heat of vaporization in J/kg or
=
(from liquid to vapour) J/g, Q is the total heat in joules (J), m is the mass of
vapour change from liquid in kg or g.
11 Thermal or heat transfer In solid = conduction
In liquid and gas = convection and also convection current
(hot matter goes up and cold matter comes down)
In vacuum = radiation
12 Emitters and Radiators Dull black surface = good emitter, good radiator, bad reflector
Bright shiny surface = poor emitter, poor radiator, good reflector
13 Another name for heat radiation Infrared radiation or radiant heat
14 Melting point Change solid into liquid, energy weaken the molecular bond, no
change in temperature, molecules move around each other
15 Boiling point Change liquid into gas, energy break molecular bond and
molecules escape the liquid, average kinetic energy increase, no
change in temperature, molecule are free to move
16 Condensation Change gas to liquid, energy release, bonds become stronger
17 Solidification Change liquid to solid, energy release bonds become very strong
18 Evaporation Change liquid to gas at any temperature, temperature of liquid
decreases, happens only at the surface
Prepared by Faisal Jaffer Revised on 21 June 2010 Page 2
