Question of the Day – Work, Power and Energy
Challenge your understanding of work, power and energy through real-world IB Physics conceptual MCQs.
2026-05-16 · 5 questions
Question of the Day – Work, Power and Energy
Challenge your understanding of work, power and energy through real-world IB Physics conceptual MCQs.
Question 1 of 5
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Q1. A student pushes a heavy box across a rough floor with a constant force, but the box does not move. What can be concluded about the work done on the box by the student?
- Positive work is done
- Negative work is done
- No work is done Correct
- Maximum work is done
Why
Work requires displacement. Since the box does not move, displacement is zero, so the work done on the box is zero.
Q2. Two elevators lift the same load to the same height. Elevator A takes 20 s while Elevator B takes 10 s. Which statement is correct?
- Elevator A does more work
- Elevator B does more work
- Both do the same work but Elevator B has greater power Correct
- Both have the same power
Why
Both elevators increase the gravitational potential energy by the same amount, so the work done is equal. Power depends on how quickly the work is done.
Q3. A cyclist moving at high speed suddenly applies the brakes. What happens to the cyclist’s kinetic energy?
- It is destroyed completely
- It changes mainly into thermal energy Correct
- It changes into gravitational potential energy
- It remains constant
Why
Friction between the brakes and wheels converts kinetic energy into thermal energy, slowing the cyclist down.
Q4. A person carries a backpack while walking horizontally at constant speed on a flat road. What is the work done by the upward force on the backpack?
- Positive
- Negative
- Zero Correct
- Maximum
Why
The upward force acts vertically while displacement is horizontal. Since the angle between them is 90°, the work done is zero.
Q5. A car engine is redesigned so that the same amount of fuel allows the car to travel a longer distance. Which statement best explains this improvement?
- The engine produces more energy from nowhere
- The engine wastes less energy Correct
- The car has more mass
- The car gains more gravitational energy
Why
A more efficient engine converts a greater fraction of the fuel’s chemical energy into useful kinetic energy instead of losing it as heat or sound.