Lesson 5 – Work, Energy and Power Objective Type Previous Questions (With Answers & Explanations)
The following objective questions are selected from previous Intermediate and competitive exam patterns. Each question includes a clear explanation to help students avoid common mistakes.
MCQ – Set 1 (Very Frequently Asked)
Q1. A body moves in a circular path. The work done by the centripetal force is:
a) Maximum
b) Minimum
c) Zero
d) Positive
Answer: (c)
Explanation: Centripetal force always acts perpendicular to the direction of displacement. Since cos 90° = 0, work done is zero.
Q2. The kinetic energy of a body depends on:
a) Velocity
b) Square of velocity
c) Acceleration
d) Time
Answer: (b)
Explanation: Kinetic energy = ½ mv². It depends on the square of velocity, not velocity directly.
Q3. If the velocity of a body is doubled, its kinetic energy becomes:
a) Doubled
b) Tripled
c) Four times
d) Half
Answer: (c)
Explanation: Since KE ∝ v², doubling velocity makes KE = (2²) = 4 times.
Q4. The SI unit of power is:
a) Joule
b) Newton
c) Watt
d) Erg
Answer: (c)
Explanation: Power = Work / Time. SI unit = Joule / second = Watt.
Q5. A force acts on a body, but no displacement occurs. The work done is:
a) Positive
b) Negative
c) Maximum
d) Zero
Answer: (d)
Explanation: Work = F s cosθ. If displacement s = 0, then work done = 0.
MCQ – Set 2 (Previous Board Level)
Q6. The work–energy theorem states that work done is equal to:
a) Kinetic energy
b) Potential energy
c) Change in kinetic energy
d) Total energy
Answer: (c)
Explanation: Work–energy theorem says: Work done by net force = change in kinetic energy.
Q7. A body moving with uniform velocity has:
a) Increasing kinetic energy
b) Decreasing kinetic energy
c) Constant kinetic energy
d) Zero kinetic energy
Answer: (c)
Explanation: Uniform velocity means velocity is constant. Since KE depends on v², KE remains constant.
Q8. Work done by friction is:
a) Always positive
b) Always negative
c) Zero
d) Maximum
Answer: (b)
Explanation: Friction always opposes motion, so force and displacement are in opposite directions → work done is negative.
Q9. Power of a body is zero when:
a) Force is maximum
b) Velocity is zero
c) Energy is maximum
d) Displacement is maximum
Answer: (b)
Explanation: Instantaneous power P = F · v. If velocity v = 0, power = 0.
Q10. Which of the following is a conservative force?
a) Friction
b) Air resistance
c) Gravitational force
d) Viscous force
Answer: (c)
Explanation: Gravitational force depends only on position and not on path, hence it is a conservative force.
Assertion–Reason Type (Previous Pattern)
Q11. Assertion: Work done by centripetal force is zero.
Reason: Centripetal force is perpendicular to velocity.
a) Both true and reason explains assertion
b) Both true but reason does not explain
c) Assertion true, reason false
d) Both false
Answer: (a)
Explanation: Since force is perpendicular to velocity (and displacement), cos 90° = 0, hence work done is zero.
Objective Exam Strategy
- Read question carefully before choosing option.
- Recall formula first, then analyze.
- Watch for keywords: perpendicular, constant velocity, zero displacement.
- Eliminate wrong options logically.
“Objective questions test understanding, not guessing.”
Work, Energy & Power – Complete Physics Library
This is the MASTER LIBRARY PAGE for the complete chapter Work, Energy and Power, prepared for Intermediate, IIT-JEE (Main & Advanced), NEET and competitive exams.
All concepts are explained from basic to IIT level, including theory, derivations, numerical problems, objective questions, previous year questions, tough IIT problems, tricks and cautions.
📚 Complete Lesson Index (Part 1 – Part 39)
- Part 1 – Introduction to Work
- Part 2 – Types of Work
- Part 3 – Variable Force & Graphs
- Part 4 – Kinetic Energy
- Part 5 – Work–Energy Theorem
- Part 6 – Potential Energy
- Part 7 – Conservative Forces
- Part 8 – Mechanical Energy
- Part 9 – Power
- Part 10 – Power Applications
- Part 11
- Part 12
- Part 13
- Part 14
- Part 15
- Part 16
- Part 17
- Part 18
- Part 19
- Part 20
- Part 21
- Part 22
- Part 23
- Part 24
- Part 25
- Part 26
- Part 27
- Part 28
- Part 29
- Part 30
- Part 31
- Part 32
- Part 33
- Part 34
- Part 35
- Part 36
- Part 37
- Part 38
- Part 39 – Final IIT Tough Problems & Solutions
Prepared by: Shaktimatha Learning 🌱
Strong Concepts • Smart Practice • Exam Success
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