Physics - Topic 3 - Energy

Question 1

State the equation that links gravitational energy, mass, gravitational field strength and height

Answer 1

Gravitational energy = mass x gravitational field strength x change in height

Question 2

What is the value of gravitational field strength (g) on Earth

Answer 2

10 (9.8)

Question 3

State the equation that links kinetic energy, mass and velocity

Answer 3

Kinetic energy = ½ x mass x v²

Question 4

List the 5 different energy stores

Answer 4

Chemical, kinetic, elastic, gravitational, nuclear, thermal

Question 5

List the 9 different energy types

Answer 5

Chemical potential, elastic potential, gravitational potential, nuclear, kinetic, electrical, light, sound, thermal

Question 6

A light bulb transfers 20J of electrical energy to 5J of light energy. Calculate the efficiency of the bulb.

Answer 6

5÷20 = 0.25 (25%)

Question 7

State the equation to calculate efficiency

Answer 7

Efficiency = useful energy transferred ÷ total energy supplied

Question 8

Explain how the efficiency of a motor can be increased

Answer 8

Oil it to reduce friction. This will reduce heat dissipated

Question 9

Explain how the efficiency of a bike could be increased

Answer 9

oil the chain to reduce friction. This will reduce the heat dissipated.

Question 10

Explain what is meant by conservation of energy

Answer 10

Energy can not be created or destroyed, only transferred

Question 11

Explain how the efficiency of a boiler or kettle could be increased

Answer 11

Insulate it to reduce the heat energy dissipated to the surroundings

Question 12

What does thermal conductivity mean?

Answer 12

The ability of a material to transfer energy through heating

Question 13

There are two houses, one house has walls twice as thick. Which house would have the higher thermal conductivity? Which house would lose heat faster?

Answer 13

The house with thicker walls would have lower thermal conductivity and lose heat slower.
The house with thinner walls would have higher thermal conductivity and lose heat faster.

Question 14

Name the different fossil fuels

Answer 14

Oil, coal, natural gas

Question 15

Describe two disadvantages of using fossil fuels to generate energy

Answer 15

They are non-renewable. They release carbon dioxide and increase global warming.

Question 16

Name an advantage of using natural gas rather than coal to generate electricity

Answer 16

It produces less carbon dioxide.

Question 17

State an advantage of using nuclear power over fossil fuels

Answer 17

It produces only water vapour and no carbon dioxide

Question 18

State a disadvantage of using nuclear power to generate electricity

Answer 18

It produces radioactive waste. It is very expensive to decommission.

Question 19

Name different renewable energy resources

Answer 19

Wind, solar, geothermal, tidal, hydroelectric, biofuel