Chapter-6 Energy Work and Power — Online MCQ Test
PHYSICS · Grade 10 · IGCSE cambridge
Practice Chapter-6 Energy Work and Power with a free chapter-wise online MCQ test.
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.
Chapter-6 Energy Work and Power — Important Questions & Answers
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.
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.
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.
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.
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.
Useful output = 5000 - 4000 = 1000 J. Efficiency = (1000/5000) × 100% = 20%. Heat and sound represent energy dissipation to the surroundings.