Equations

Question 1

Kinetic energy

Answer 1

kinetic energy = 0.5 × mass × (speed)2

Question 2

Elastic potential energy

Answer 2

elastic potential energy = 0.5 × spring constant × (extension)2

Question 3

Gravitational potential energy

Answer 3

gravitational potential energy = mass × gravitational field strength × height

Question 4

Change in thermal energy

Answer 4

change in thermal energy = mass × specific heat capacity × temperature change

Question 5

Power (energy transferred)

Answer 5

power = energy transferred/time

Question 6

Power (work done)

Answer 6

power= work done/time

Question 7

Efficiency (useful output energy transfer)

Answer 7

efficiency = useful output energy transfer / total input energy transfer

Question 8

Efficiency (useful power output)

Answer 8

efficiency= useful power output/total power input

Question 9

Charge flow

Answer 9

charge flow = current × time

Question 10

Potential difference

Answer 10

potential difference = current × resistance

Question 11

Power

Answer 11

power = potential difference × current

Question 12

Power

Answer 12

power = (current)^2 × resistance

Question 13

Energy transferred

Answer 13

energy transferred = power × time

Question 14

Energy transferred (charge flow)

Answer 14

energy transferred = charge flow × potential difference

Question 15

Thermal energy for a change of state

Answer 15

transferred = charge flow × potential difference

Question 16

density

Answer 16

density= mass / volume

Question 17

Thermal energy for a change of state

Answer 17

Thermal energy for a change of state= mass x specific latent heat

Question 18

For gases: pressure

Answer 18

pressure x volume = constant

Question 19

weight

Answer 19

Mass x gravitational field strength

Question 20

Work done

Answer 20

Work done= force x distance (along the line of action of the force)