Work Done — Homi Bhabha Exam Physics MCQs with Solutions
Free Homi Bhabha Exam Physics Work Done MCQs with step-by-step solutions (7 questions). Part of Work, Energy & Power. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Work Done · medium · numerical
A force of 20 N moves a body 5 m in the direction of the force. The work done is:
A. 25 J
B. 4 J
C. 15 J
D. 100 J ✓ Correct
Solution: Work $= F \times s = 20 \times 5 = 100$ J.
Q2 — Work Done · hard · theory
A coolie carrying a load on his head walks a distance on a level platform. The work done by him against gravity is:
A. maximum
B. zero ✓ Correct
C. equal to the distance walked
D. equal to the weight of the load
Solution: The load moves horizontally while gravity acts vertically, so the displacement in the direction of the gravitational force is zero — work done against gravity is zero.
Q3 — Work Done · hard · numerical
A force of 10 N acts on a body but the body does not move. The work done is:
A. 0 J ✓ Correct
B. 1 J
C. 10 J
D. 100 J
Solution: Work $= F \times s$; with zero displacement the work done is zero, however large the force.
Q4 — Work Done · medium · theory
Work is done on a body only when:
A. a force acts and the body moves in the direction of (a component of) the force ✓ Correct
B. the body is at rest
C. the body has energy
D. a force acts on the body
Solution: Work requires both a force and a displacement along the force; either alone gives zero work.
Q5 — Work Done · hard · numerical
A body is lifted vertically through 4 m by applying a force equal to its weight of 25 N. The work done against gravity is:
A. 29 J
B. 21 J
C. 100 J ✓ Correct
D. 6.25 J
Solution: Work $= F \times h = 25 \times 4 = 100$ J.
Q6 — Work Done · medium · theory
The SI unit of work is the joule, which is equivalent to:
A. newton per metre
B. newton·metre (N·m) ✓ Correct
C. kilogram·metre
D. watt·metre
Solution: 1 joule = 1 newton × 1 metre (N·m).
Q7 — Work Done · hard · theory
When friction acts on a body opposite to its motion, the work done by friction is:
A. zero
B. infinite
C. positive
D. negative ✓ Correct
Solution: Friction acts opposite to the displacement, so the work it does on the body is negative.