Year 7 · Science · Energy · Lesson 2
Conservation of energy and efficiency
The law of conservation of energy, useful and wasted energy, Sankey diagrams, efficiency calculations and ways to reduce wasted energy.
18-minute video lesson
Teaching, worked examples and 20 practice questions solved step by step.
Watch free for a monthWhat your child will learn
- State the law of conservation of energy
- Calculate wasted energy
- Calculate efficiency
- Interpret Sankey diagrams
The method
- Wasted.
- Efficiency.
- x 100.
- Check.
Key words: conservation of energy, wasted energy, dissipate, efficiency, Sankey diagram, insulation.
Worked examples
The first three practice questions from the lesson, with every step.
Question 1
Can energy be created?
- Step 1: Law
Answer: no
Question 2
Can energy be destroyed?
- Step 1: Law
Answer: no
Question 3
What happens to energy instead?
- Step 1: Moves
Answer: it is transferred between stores