Energy is measured in joules and a moving car carries mostly kinetic energy, so this Year 7 sheet pairs the unit of energy with its most common moving form. The key also records that energy is never created or destroyed.
Key Takeaways
The unit of energy is the joule (Q1).
A moving car has mostly kinetic energy (Q2).
Energy is never created or destroyed (Q6).
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.What is the unit of energy?
(a) joule(b) newton(c) watt(d) pascal
2.A moving car has mostly...
(a) kinetic energy(b) elastic potential energy(c) nuclear energy(d) sound energy
3.A stretched rubber band stores...
(a) kinetic energy(b) elastic potential energy(c) light energy(d) chemical energy
4.A light bulb converts electrical energy mainly into...
(a) light and thermal energy(b) kinetic and sound energy(c) chemical energy(d) nuclear energy
5.Which of these is a renewable energy source?
(a) coal(b) natural gas(c) solar energy(d) oil
6.The Law of Conservation of Energy states that energy...
(a) can be created easily(b) is never created or destroyed(c) is always destroyed when used(d) disappears when used
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.State the unit of energy and give its symbol.
8.Name two stores of energy and give one example of each.
9.Describe the energy transfers that happen when an electric kettle boils water.
10.What is a renewable energy source? Give one example.
11.Explain why a ball dropped from a height speeds up as it falls.
12.State one disadvantage of burning fossil fuels.
13.State the Law of Conservation of Energy.
14.When a compressed spring is released, which energy store changes and what does it change into?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A 50 W lamp is switched on for 120 s. Use the equation energy = power × time to calculate the energy transferred in joules.
16.A fan transfers 300 J of energy every second. How much energy does it transfer in 10 s?
17.A lamp receives 100 J of electrical energy and transfers 20 J as useful light. Calculate the energy wasted as heat.
18.A car engine receives 1000 J of chemical energy and transfers 350 J to useful kinetic energy. Calculate the wasted energy.
19.A ball has 40 J of potential energy at the top of a hill. Assuming no energy is lost, how much kinetic energy will it have at the bottom?
20.A phone charger uses 5 W of power for 3600 s. Use energy = power × time to calculate the energy transferred in joules.
Answer Key
1. a) joule
2. a) kinetic energy
3. b) elastic potential energy
4. a) light and thermal energy
5. c) solar energy
6. b) is never created or destroyed
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End of Worksheet
People Also Ask
What is the unit of energy?
The joule, option (a) in this worksheet (Q1).
What kind of energy does a moving car have mostly?
Kinetic energy, option (a) in this worksheet (Q2).
What does the conservation law say?
Energy is never created or destroyed, option (b) in this worksheet (Q6).
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