Common Equations

Question 1

Work Done

W = Fs

Answer 1

Work Done = Force applied * Displacement

Joules, J = Newtons, N * Metres, m

Question 2

Gravitational Potential

∆E_p = mg∆h

Answer 2

Change in GPE = Mass * Gravitational Field Strength * Change in Height

Joules, J = kg * N/kg * m

Question 3

Elastic Potential

E_e = 1/2 ke²

Answer 3

Elastic Potential = 1/2 * Spring Constant * Extension²

Joules, J = 1/2 * N/m * m²

Question 4

Kinetic Energy

E_k = 1/2 mv²

Answer 4

Kinetic Energy = 1/2 * Mass * Velocity²

Joules, J = 1/2 * kg * m/s²

Question 5

Thermal Energy Change

∆E = mc∆θ

Answer 5

Energy = Mass * Specific Heat Capacity * Change in Temperature

Joules, J = kg * J/kg °C * °C

Question 6

Power

P = E/t

Answer 6

Power = Energy transferred / Time Taken

Watts, W = Joules, J / seconds, s

Question 7

Power

P = W/t

Answer 7

Power = Work Done / Time Taken

Watts, W = Joules, J / seconds, s

Question 8

Efficiency

% = E_u/E_t

Answer 8

Efficiency = Useful energy output / Total energy input

% = Joules, J / Joules, J

Question 9

Efficiency

% = P_u/P_t

Answer 9

Efficiency = Useful power output / Total power input

% = Watts, W / Watts, W

Question 10

Charge Flow

Q = It

Answer 10

Charge Flow = Current * Time Taken

coulombs, C = ampères, A * seconds, s

Question 11

Potential Difference

V = IR

Answer 11

Potential Difference = Current * Resistance

Volts, V = Ampères, A * Ohms, Ω

Question 12

Power

P = VI

Answer 12

Power = Potential Difference * Current

Watts, W = Volts, V * Ampères, A

Question 13

Power

P = I²R

Answer 13

Power = Current² * Resistance

Watts, W = Ampères, A² * Ohms, Ω

Question 14

Energy

E = Pt

Answer 14

Energy transferred = Power * Time Taken

Joules, J = Watts, W * Seconds, s

Question 15

Energy

E = QV

Answer 15

Energy transferred = Charge * Potential Difference

Joules, J = Coulombs, C * Volts, V

Question 16

Density

ρ = m/V

Answer 16

Density = Mass / Volume

kg/m³ = kg / m³

Question 17

Thermal Energy Change

∆E = mc∆θ

Answer 17

Energy = Mass * Specific Heat Capacity * Change in Temperature

Joules, J = kg * J/kg °C * °C

Question 18

Energy for a State Change

E = mL

Answer 18

Energy for a State Change = Mass * Specific Latent Heat

Joules, J = kg * J/kg

Question 19

Pressure and Volume

p₁V₁ = p₂V₂

Answer 19

Pressure₁ * Volume₁ = Pressure₂ * Volume₂

Pascals, Pa * m³ = constant

Question 20

Alpha Particle

α

Answer 20

4
He
2

Helium-4 Nucleus

Question 21

Beta Particle

β

Answer 21

0
e
-1

Ejected Electron