Work by Variable Force — JEE Main Physics MCQs with Solutions
Free JEE Main Physics Work by Variable Force MCQs with step-by-step solutions (2 questions). Part of Work, Power and Energy. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Work by Variable Force · easy · numerical
The work required to stretch a spring of k = 400 N/m by 5 cm from its natural length is:
A. 0.5 J ✓ Correct
B. 0.05 J
C. 1.0 J
D. 10 J
Solution: W = ½kx² = ½ × 400 × (0.05)² = 200 × 0.0025 = 0.5 J.
Q2 — Work by Variable Force · medium · numerical
A spring stores 4 J when stretched by 2 cm. The energy stored when it is stretched by 4 cm is:
A. 4 J
B. 32 J
C. 8 J
D. 16 J ✓ Correct
Solution: U = ½kx² ∝ x². Doubling x quadruples the energy: 4 × 4 = 16 J.