Conservation Of Energy

Question 1

What is the equation for gravitational potential energy (GPE)?

Answer 1

GPE = mass × gravitational field strength × height (GPE = mgh)

Question 2

What is the unit of gravitational potential energy?

Answer 2

Joules (J)

Question 3

What is the equation for kinetic energy (KE)?

Answer 3

KE = ½ × mass × speed² (KE = ½mv²)

Question 4

What is the unit of kinetic energy?

Answer 4

Joules (J)

Question 5

What energy transfer happens when an object is projected upwards?

Answer 5

Kinetic energy is transferred to gravitational potential energy

Question 6

What energy transfer happens when an object is moving upwards then falls down?

Answer 6

Gravitational potential energy is transferred back to kinetic energy

Question 7

What energy transfer occurs when a vehicle slows down?

Answer 7

Kinetic energy is transferred to thermal energy through the brakes

Question 8

What energy transfer happens in a kettle?

Answer 8

Electrical energy is transferred to thermal energy

Question 9

What is meant by ‘energy dissipation’?

Answer 9

It means energy is spread out and lost to the surroundings, often as heat

Question 10

What is a ‘closed system’?

Answer 10

A system where no energy enters or leaves – total energy remains constant

Question 11

What is meant by ‘conservation of energy’?

Answer 11

Energy cannot be created or destroyed, only transferred or stored in different ways

Question 12

In a closed system, is energy ever lost?

Answer 12

No, in a closed system no energy is lost

Question 13

Give an example of an energy transfer diagram

Answer 13

Electric energy → Bulb → Light (useful) + Heat (wasted)

Question 14

Why are motors often inefficient?

Answer 14

Because some energy is wasted as heat

Question 15

State the efficiency equation

Answer 15

Efficiency = (useful energy output ÷ total energy input) × 100

Question 16

What is waste energy?

Answer 16

Energy that is not usefully transferred, usually lost as heat or sound

Question 17

How can waste energy be reduced in machines?

Answer 17

By using lubrication to reduce friction or thermal insulation to reduce heat loss

Question 18

What does thermal insulation do?

Answer 18

Reduces heat loss to surroundings by slowing down energy transfer

Question 19

What is the role of cavity wall insulation in buildings?

Answer 19

It traps air, reducing heat loss by convection and conduction

Question 20

What happens to energy in a moving object that hits an obstacle?

Answer 20

Kinetic energy is transferred to thermal energy or sound

Question 21

What is meant by ‘useful energy’?

Answer 21

Energy that is transferred in the desired form for a specific task

Question 22

What is meant by ‘mechanical waste energy’?

Answer 22

Energy lost due to friction or air resistance, usually as heat

Question 23

Name three non-renewable energy sources

Answer 23

Coal, Oil, Natural Gas

Question 24

Name three renewable energy sources

Answer 24

Solar, Wind, Hydro-electric

Question 25

Give two disadvantages of fossil fuels

Answer 25

They release greenhouse gases and contribute to global warming

Question 26

Give one disadvantage of nuclear energy

Answer 26

Produces radioactive waste that must be stored safely for many years

Question 27

Give one advantage of wind power

Answer 27

It is renewable and produces no greenhouse gases

Question 28

Give one disadvantage of solar power

Answer 28

Only works in daylight and weather-dependent

Question 29

Why is renewable energy becoming more important?

Answer 29

"Fossil fuels are finite and cause environmental