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Conservation of energy and wasted energy

8th grade (Year 9 in England) · 16 questions · Common Core: NGSS.MS-PS3-5, NGSS.HS-PS3-1 · England: KS3 Physics: Energy (changes in systems), KS4 Combined Science: Energy

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Question 1
A kettle is supplied with 500 J of energy. It transfers 200 J usefully. How much energy is wasted, in J?
AnswerJ
2
Question 2
Conservation of energy: which statement is NOT true?
- A. A Sankey diagram shows useful and wasted energy.
- B. A machine can give out more energy than it takes in.
- C. Wasted energy is often transferred to the surroundings by heating.
- D. No real machine is 100% efficient.
3
Question 3
A ball is dropped and each bounce is lower. Where did the energy go?
- A. It was destroyed
- B. It went into the ball's mass
- C. Gravity took it
- D. It was transferred to the surroundings as heat and sound
Question 4
A kettle is supplied with 2000 J of energy. It transfers 1500 J usefully. How much energy is wasted, in J?
AnswerJ
5
Question 5
Conservation of energy: which statement is NOT true?
- A. Wasted energy is often transferred to the surroundings by heating.
- B. The total energy in a closed system stays the same.
- C. A Sankey diagram shows useful and wasted energy.
- D. Energy is used up and disappears.
6
Question 6
What does the law of conservation of energy say?
- A. Machines create energy
- B. Energy cannot be created or destroyed, only transferred
- C. Energy is used up and disappears
- D. Energy is always destroyed as heat
Question 7
A kettle is supplied with 2000 J of energy. It transfers 1800 J usefully. How much energy is wasted, in J?
AnswerJ
8
Question 8
Conservation of energy: which statement is NOT true?
- A. A Sankey diagram shows useful and wasted energy.
- B. Wasted energy is often transferred to the surroundings by heating.
- C. Energy is used up and disappears.
- D. The total energy in a closed system stays the same.
9
Question 9
Where does most wasted energy usually end up?
- A. heating the surroundings
- B. inside the plug
- C. destroyed
- D. back in the battery
Question 10
A speaker is supplied with 1200 J of energy. It transfers 240 J usefully. How much energy is wasted, in J?
AnswerJ
11
Question 11
Conservation of energy: which statement is NOT true?
- A. Wasted energy is often transferred to the surroundings by heating.
- B. No real machine is 100% efficient.
- C. A machine can give out more energy than it takes in.
- D. A Sankey diagram shows useful and wasted energy.
12
Question 12
Where does most wasted energy usually end up?
- A. heating the surroundings
- B. destroyed
- C. back in the battery
- D. inside the plug
Question 13
A speaker is supplied with 200 J of energy. It transfers 180 J usefully. How much energy is wasted, in J?
AnswerJ
14
Question 14
Conservation of energy: which statement is NOT true?
- A. The total energy in a closed system stays the same.
- B. Wasted energy is destroyed.
- C. A Sankey diagram shows useful and wasted energy.
- D. No real machine is 100% efficient.
15
Question 15
Where does most wasted energy usually end up?
- A. inside the plug
- B. heating the surroundings
- C. destroyed
- D. back in the battery
Question 16
A motor is supplied with 1200 J of energy. It transfers 300 J usefully. How much energy is wasted, in J?
AnswerJ

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Answer key: Conservation of energy and wasted energy

1. 300 J
2. B. A machine can give out more energy than it takes in.
3. D. It was transferred to the surroundings as heat and sound
4. 500 J
5. D. Energy is used up and disappears.
6. B. Energy cannot be created or destroyed, only transferred
7. 200 J
8. C. Energy is used up and disappears.
9. A. heating the surroundings
10. 960 J
11. C. A machine can give out more energy than it takes in.
12. A. heating the surroundings
13. 20 J
14. B. Wasted energy is destroyed.
15. B. heating the surroundings
16. 900 J