Previous IIT / JEE Objective Questions
Work, Energy & Power – PAGE 3
This page contains advanced objective questions where students usually lose marks due to wrong assumptions, hidden energy loss, or poor logic.
Q26. (IIT-JEE Advanced)
A particle moves under a force F = −kx. Which statement is correct?
Answer: Total mechanical energy remains constant
Reason:
Force depends only on position → conservative force.
Trap: Students confuse restoring force with dissipative force.
Q27. (JEE Main)
A block slides down a rough incline and reaches the bottom with speed v. If the incline angle is doubled, what happens to speed (qualitative)?
Answer: Speed may increase or decrease
Explanation:
Friction and gravity components change differently.
IIT Insight: Never assume monotonic change.
Q28. (IIT-JEE Advanced)
A particle moves in a vertical circle. At the lowest point, kinetic energy is maximum. Which statement is true?
Answer: Potential energy is minimum
Why:
Total mechanical energy = constant.
Q29. (JEE Main)
If the work done by a force is negative, which of the following is true?
Answer: Force opposes motion
Reason:
W = F·s < 0 ⇒ opposite direction.
Q30. (IIT-JEE Advanced)
A particle moves in a potential field U(x). Which condition defines stable equilibrium?
Answer: d²U/dx² > 0
Logic:
Small displacement increases potential energy.
Q31. (JEE Main)
A block slides on a horizontal surface with constant speed. Which is correct?
Answer: Power supplied equals power lost due to friction
Explanation:
Net work = 0 → input power balances loss.
Q32. (IIT-JEE Advanced)
A particle of mass m is attached to a spring and oscillates. Which quantity remains constant (ideal case)?
Answer: Total mechanical energy
Insight:
Spring force is conservative.
Q33. (JEE Main)
A particle is thrown upward. During ascent, which quantity continuously decreases?
Answer: Kinetic energy
Why:
Work done by gravity is negative.
Q34. (IIT-JEE Advanced)
If a particle moves in a circle with constant speed, which quantity changes continuously?
Answer: Direction of velocity
Trap:
Speed constant ≠ velocity constant.
Q35. (JEE Main)
A particle has zero kinetic energy. Which statement must be true?
Answer: Particle is momentarily at rest
Note:
Force and acceleration need not be zero.
End of PAGE 3
PAGE 3 focuses on conceptual traps and equilibrium logic — a favorite area of IIT examiners.
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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