Equations Flashcards
Speed
Speed = distance / time
Acceleration
Acceleration = final velocity - initial velocity / time
Weight
Weight = mass x gravity
Density
density = mass / volume
Force
Force = mass x acceleration
Hooke’s law
Force = spring constant x extension in metres
Moment of a force
Moment of force = force x perpendicular distance from the pivot in metres
Principle of moments
Total clockwise moment = total anti-clockwise moment
F1d1 = F2d2
Work done
Work done = force x distance
Kinetic energy
Kinetic energy = 1/2 x mass x velocity^2
Gravitational potential energy
GPE = mass x gravity x height
Conservation of energy applied to falling objects
Loss of gravitational potential = gain of kinetic
mass x gravity x height = 1/2 x mass x velocity^2
Power
Power = work done / time taken
Power = energy transfer / time taken
Efficiency
Efficiency = useful energy output / total energy input x 100
Pressure
Pressure = force / area
Pressure due to liquid
pressure = density x acceleration due to gravity x height
Momentum
Momentum = mass x velocity
Pressure and volume relationship (Boyle’s law)
pV = constant
p1 x V1 = p2 x V2
Specific heat capacity
Heat energy = mass x specific heat capacity x change in temperature
Specific latent heat of fusion
Lf = total heat / mass of liquid change
Specific latent heat of vaporisation
Lv = total heat / mass of vapour change from liquid
Wave equation
Velocity = frequency x wavelength
Frequency
Frequency = 1 / time period of wave
Refractive index n
N = sin i / sin r
N = speed of light in air or vacuum / speed of light in any other medium
N= 1/sin c
C is the critical angle
Echo
Speed of sound waves = 2 x distance / time
Current
Current = charge / time
Resistance
Resistance = voltage / current
Potential difference (or voltage)
Voltage = energy / charge
Resistance in series
R = R1 + R2….
Resistance in parallel
1/R = 1/R1 + 1/R2 …
Potential divider
V1/V2 =R1/R2
V2 = (R2 / R1 + R2) x V
V1 = (R1 / R1 + R2) x V
Electrical Power
Power = current x voltage
Electrical energy
Electrical energy = current x voltage x time
Transformer
Voltage in primary coil / voltage in secondary coil = No. of turns in primary coil / no. of turns in secondary coil
If 100% efficient
Power in = power out
Current in primary coil x voltage in primary coil = current in secondary coil x voltage in secondary coil
Relative density
Density of substance / density of water
