Chapter Exam

Chapter-6 Energy Work and Power — Online MCQ Test

Q: Which of the following is the SI unit of work?

Answer: A. Joule (J) — Work is measured in Joules (J), which is equivalent to Newton-metre (N·m). Watt is the unit of power, not work.

Q: Power is defined as the rate of _____ transfer or the rate at which _____ is done.

Answer: B. energy; work — Power is defined as the rate of energy transfer or the rate at which work is done. The formula is P = W/t or P = E/t.

Q: A machine has an efficiency of 60%. If the input energy is 500 J, what is the useful output energy?

Answer: A. 300 J — Efficiency = (Useful Output Energy / Input Energy) × 100%. Therefore, Useful Output = 0.60 × 500 = 300 J.

Q: A ball is thrown vertically upwards. At the moment it reaches its maximum height, which type of energy is maximum?

Answer: B. Gravitational potential energy — At maximum height, the velocity becomes zero, so kinetic energy is zero. All the initial kinetic energy has been converted to gravitational potential energy.

Q: A device transfers 5000 J of input energy. If 4000 J is wasted as heat and sound, what is the percentage efficiency and what type of energy loss is this?

Answer: B. 20% efficient; energy dissipation — Useful output = 5000 - 4000 = 1000 J. Efficiency = (1000/5000) × 100% = 20%. Heat and sound represent energy dissipation to the surroundings.

PHYSICS · Grade 10 · IGCSE cambridge

Practice Chapter-6 Energy Work and Power with a free chapter-wise online MCQ test for IGCSE cambridge Grade 10 PHYSICS. This chapter covers: Energy stores and transfers work done power efficiency and energy resources for generating electricity.. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-6 Energy Work and Power — Important Questions & Answers (FAQ)

Frequently asked questions from IGCSE cambridge Grade 10 PHYSICS — Chapter-6 Energy Work and Power, with answers and explanations. These are sample questions; the exam has its own separate question set.

Which of the following is the SI unit of work?

A. Joule (J) ✓
B. Newton (N)
C. Watt (W)
D. Pascal (Pa)

Answer: A. Joule (J)
Work is measured in Joules (J), which is equivalent to Newton-metre (N·m). Watt is the unit of power, not work.

Power is defined as the rate of _____ transfer or the rate at which _____ is done.

A. heat; temperature
B. energy; work ✓
C. force; displacement
D. momentum; velocity

Answer: B. energy; work
Power is defined as the rate of energy transfer or the rate at which work is done. The formula is P = W/t or P = E/t.

A machine has an efficiency of 60%. If the input energy is 500 J, what is the useful output energy?

A. 300 J ✓
B. 500 J
C. 833 J
D. 200 J

Answer: A. 300 J
Efficiency = (Useful Output Energy / Input Energy) × 100%. Therefore, Useful Output = 0.60 × 500 = 300 J.

A ball is thrown vertically upwards. At the moment it reaches its maximum height, which type of energy is maximum?

A. Kinetic energy
B. Gravitational potential energy ✓
C. Elastic potential energy
D. Thermal energy

Answer: B. Gravitational potential energy
At maximum height, the velocity becomes zero, so kinetic energy is zero. All the initial kinetic energy has been converted to gravitational potential energy.

A device transfers 5000 J of input energy. If 4000 J is wasted as heat and sound, what is the percentage efficiency and what type of energy loss is this?

A. 80% efficient; useful energy output
B. 20% efficient; energy dissipation ✓
C. 80% efficient; energy conservation
D. 20% efficient; energy storage

Answer: B. 20% efficient; energy dissipation
Useful output = 5000 - 4000 = 1000 J. Efficiency = (1000/5000) × 100% = 20%. Heat and sound represent energy dissipation to the surroundings.