Topic 1

Question 1

what’s the equation for kinetic energy

Answer 1

1/2mv^2
Energy(J), Mass(kg), Velocity(m/s)

Question 2

equation for elastic potential energy

Answer 2

1/2kx^2
Energy(J), Spring constant(N/m), extension(m)

Question 3

equation for gravity potential energy

Answer 3

mass x gravitational field strength (n/kg)x height

Question 4

define specific heat capacity

Answer 4

amount of energy needed to raise the temp of 1kg of substance by 1°C

Question 5

Give the units for specific heat capacity

Answer 5

J/°C/kg

Question 6

definition of power

Answer 6

rate at which energy is transferred or the rate at which work is done

Question 7

give two equations for power

Answer 7

power=energy transferred/time
power=work done/time

Question 8

unit of power

Answer 8

Watts. W

Question 9

two motors lift the same pass through the same height motor A does this in half the time of motor B. Which dissipates the most power

Answer 9

Motor A, energy transferred is the same but time taken is less

Question 10

describe the energy changes when a ball is thrown up in the air and returns to its starting position, ignoring air resistance

Answer 10

Upwards, ke is converted to gpe
peak, max gpe 0ke
downwards, gpe is converted to ke

Question 12

describe energy transfer for a bungee jumper

Answer 12

when falling gpe is converted to ke of jumper
as cord tightens, ke is converted and stored as elastic potential energy
at lowest point, jumpers initial gpe equals the epe stored in the cord

Question 13

why does a bungee jumper slow as the cord stretches

Answer 13

ke decreases as it’s converted to epe
since ke is proportional to (velocity)^2, as ke decreases, so does velocity

Question 14

give example of chemical energy store

Answer 14

food, fuel, batteries

Question 15

state 4 different stores of energy

Answer 15

kinetic, gravitational potential, elastic potential, chemical, thermal