Energy stores, transfers and efficiency
Learn Energy stores, transfers and efficiency for Year 9 pupils (ages 13–14). Free practice questions, lessons and worked examples — aligned to the UK National Curriculum.
What you'll learn
- 1
Energy is never created or destroyed — it is transferred between stores.
- 2
A rollercoaster at the top has gravitational potential energy. Going down, it transfers to kinetic. Some always transfers to thermal through friction.
- 3
Which store does a raised object have?
- 4
Common error: "energy gets used up." It does not — it spreads out into surroundings as thermal energy and becomes less useful.
- 5
What happens to "wasted" energy?
- 6
Apply it: a lamp takes in 60 J and gives out 12 J of light. Efficiency = useful ÷ total = 12 ÷ 60 = 0.2, or 20%. The other 48 J transfers to thermal.
- 7
A motor takes 200 J and usefully transfers 150 J. What is its efficiency?
Practise Energy stores, transfers and efficiency with Whizlo
Free AI-tutored lessons, unlimited practice questions, and progress tracking for ages 13–14. Aligned to the UK National Curriculum.