Chapter Exam

Chapter-5 Work Energy and Power — Online MCQ Test

Q: Work done by a constant force is defined as the product of force, displacement, and the cosine of the angle between them. What is the SI unit of work?

Answer: B. Joule — The SI unit of work is Joule (J), which equals Newton-meter (N·m).

Q: If a force of 10 N is applied on an object and it moves 5 m in the direction of the force, what is the work done?

Answer: C. 50 J — Work = Force × Displacement × cos(θ) = 10 × 5 × cos(0°) = 50 J.

Q: A ball is thrown vertically upward with initial velocity 20 m/s. Using the work-energy theorem, find the maximum height reached (g = 10 m/s²).

Answer: B. 20 m — Using work-energy theorem: -mgh = 0 - (1/2)mv²; h = v²/(2g) = 400/(2×10) = 20 m.

Q: Two objects of mass m₁ and m₂ (m₁ > m₂) are moving with the same kinetic energy. Which has greater momentum?

Answer: A. m₁ — Since KE = p²/(2m), for equal KE, the heavier object has greater momentum: p = √(2m·KE).

Q: A force F = 3x² N acts on an object from x = 1 m to x = 3 m. Calculate the work done by this variable force.

Answer: C. 26 J — Work = ∫₁³ 3x² dx = [x³]₁³ = 27 - 1 = 26 J.

PHYSICS · Grade 11 · CBSE(NCERT)

Practice Chapter-5 Work Energy and Power with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 11 PHYSICS. This chapter covers: Work done by constant and variable forces - Kinetic energy - Work-energy theorem - Potential energy - Conservative and non-conservative forces - Conservation of mechanical energy -.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter-5 Work Energy and Power — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 11 PHYSICS — Chapter-5 Work Energy and Power, with answers and explanations. These are sample questions; the exam has its own separate question set.

Work done by a constant force is defined as the product of force, displacement, and the cosine of the angle between them. What is the SI unit of work?

A. Newton
B. Joule ✓
C. Watt
D. Pascal

Answer: B. Joule
The SI unit of work is Joule (J), which equals Newton-meter (N·m).

If a force of 10 N is applied on an object and it moves 5 m in the direction of the force, what is the work done?

A. 2 J
B. 15 J
C. 50 J ✓
D. 0.5 J

Answer: C. 50 J
Work = Force × Displacement × cos(θ) = 10 × 5 × cos(0°) = 50 J.

A ball is thrown vertically upward with initial velocity 20 m/s. Using the work-energy theorem, find the maximum height reached (g = 10 m/s²).

A. 10 m
B. 20 m ✓
C. 30 m
D. 40 m

Answer: B. 20 m
Using work-energy theorem: -mgh = 0 - (1/2)mv²; h = v²/(2g) = 400/(2×10) = 20 m.

Two objects of mass m₁ and m₂ (m₁ > m₂) are moving with the same kinetic energy. Which has greater momentum?

A. m₁ ✓
B. m₂
C. Both have equal momentum
D. Cannot be determined

Answer: A. m₁
Since KE = p²/(2m), for equal KE, the heavier object has greater momentum: p = √(2m·KE).

A force F = 3x² N acts on an object from x = 1 m to x = 3 m. Calculate the work done by this variable force.

A. 16 J
B. 24 J
C. 26 J ✓
D. 52 J

Answer: C. 26 J
Work = ∫₁³ 3x² dx = [x³]₁³ = 27 - 1 = 26 J.

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