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8th grade 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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1
Question 1
How can wasted energy in a machine with moving parts be reduced?
- A. make it move faster
- B. remove the oil
- C. lubricate the parts to reduce friction
- D. paint it a darker colour
2
Question 2
Conservation of energy: which statement is NOT true?
- A. A machine can give out more energy than it takes in.
- B. No real machine is 100% efficient.
- C. Wasted energy is often transferred to the surroundings by heating.
- D. The total energy in a closed system stays the same.
Question 3
A speaker is supplied with 1000 J of energy. It transfers 900 J usefully. How much energy is wasted, in J?
AnswerJ
4
Question 4
A ball is dropped and each bounce is lower. Where did the energy go?
- A. It was transferred to the surroundings as heat and sound
- B. It was destroyed
- C. It went into the ball's mass
- D. Gravity took it
5
Question 5
Conservation of energy: which statement is NOT true?
- A. No real machine is 100% efficient.
- B. Wasted energy is often transferred to the surroundings by heating.
- C. The total energy in a closed system stays the same.
- D. Energy is used up and disappears.
Question 6
A motor is supplied with 2000 J of energy. It transfers 1200 J usefully. How much energy is wasted, in J?
AnswerJ
7
Question 7
Where does most wasted energy usually end up?
- A. back in the battery
- B. inside the plug
- C. destroyed
- D. heating the surroundings
8
Question 8
Conservation of energy: which statement is NOT true?
- A. No real machine is 100% efficient.
- B. Wasted energy is often transferred to the surroundings by heating.
- C. Wasted energy is destroyed.
- D. A Sankey diagram shows useful and wasted energy.
Question 9
A lamp is supplied with 2000 J of energy. It transfers 800 J usefully. How much energy is wasted, in J?
AnswerJ
10
Question 10
Where does most wasted energy usually end up?
- A. heating the surroundings
- B. inside the plug
- C. back in the battery
- D. destroyed
11
Question 11
Conservation of energy: which statement is NOT true?
- A. Wasted energy is often transferred to the surroundings by heating.
- B. A Sankey diagram shows useful and wasted energy.
- C. A machine can give out more energy than it takes in.
- D. No real machine is 100% efficient.
Question 12
A lamp is supplied with 1000 J of energy. It transfers 900 J usefully. How much energy is wasted, in J?
AnswerJ
13
Question 13
Where does most wasted energy usually end up?
- A. back in the battery
- B. inside the plug
- C. heating the surroundings
- D. destroyed
14
Question 14
Conservation of energy: which statement is NOT true?
- A. No real machine is 100% efficient.
- B. A Sankey diagram shows useful and wasted energy.
- C. Wasted energy is destroyed.
- D. The total energy in a closed system stays the same.
Question 15
A motor is supplied with 100 J of energy. It transfers 40 J usefully. How much energy is wasted, in J?
AnswerJ
16
Question 16
What does the law of conservation of energy say?
- A. Energy is used up and disappears
- B. Energy is always destroyed as heat
- C. Machines create energy
- D. Energy cannot be created or destroyed, only transferred

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Answer key: 8th grade energy

1. C. lubricate the parts to reduce friction
2. A. A machine can give out more energy than it takes in.
3. 100 J
4. A. It was transferred to the surroundings as heat and sound
5. D. Energy is used up and disappears.
6. 800 J
7. D. heating the surroundings
8. C. Wasted energy is destroyed.
9. 1200 J
10. A. heating the surroundings
11. C. A machine can give out more energy than it takes in.
12. 100 J
13. C. heating the surroundings
14. C. Wasted energy is destroyed.
15. 60 J
16. D. Energy cannot be created or destroyed, only transferred