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Lesson 5 – Work, Energy and Power Numerical Problems (Previous Questions)

The following numerical problems are taken from previous Intermediate exam patterns. Each solution follows the Given → Required → Formula → Substitution → Answer method to ensure full marks.

                                              

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Problem 1: Kinetic Energy

Q1. Find the kinetic energy of a body of mass 2 kg moving with a velocity of 5 m/s.

Given:
m = 2 kg
v = 5 m/s

Required: Kinetic energy

Formula:
K.E = ½ mv²

Substitution:
K.E = ½ × 2 × (5)² = 25 J

Answer: Kinetic energy = 25 J

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Problem 2: Work Done by Force

Q2. A force of 10 N acts on a body and produces a displacement of 4 m in the direction of force. Find the work done.

Given:
F = 10 N
s = 4 m

Required: Work done

Formula:
W = F s

Substitution:
W = 10 × 4 = 40 J

Answer: Work done = 40 J

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Problem 3: Change in Kinetic Energy

Q3. A body of mass 1 kg increases its speed from 2 m/s to 6 m/s. Find the change in kinetic energy.

Given:
m = 1 kg
u = 2 m/s
v = 6 m/s

Required: Change in kinetic energy

Formula:
ΔK = ½ m (v² − u²)

Substitution:
ΔK = ½ × 1 × (36 − 4) = 16 J

Answer: Change in kinetic energy = 16 J

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Problem 4: Power Calculation

Q4. Calculate the power of a machine that does 600 J of work in 10 seconds.

Given:
Work = 600 J
Time = 10 s

Required: Power

Formula:
Power = Work / Time

Substitution:
P = 600 / 10 = 60 W

Answer: Power = 60 W

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Problem 5: Work–Energy Theorem

Q5. A force of 5 N acts on a body and increases its speed from rest to 4 m/s. If the mass of the body is 1 kg, verify the work–energy theorem.

Given:
m = 1 kg
u = 0
v = 4 m/s

Required: Work done and change in kinetic energy

Kinetic Energy:
ΔK = ½ m v² = ½ × 1 × 16 = 8 J

Work done = Change in kinetic energy = 8 J

Answer: Work–energy theorem is verified.

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Problem 6: Power Using Force & Velocity

Q6. A body moves with a constant velocity of 10 m/s under a force of 2 N. Find the power developed.

Given:
F = 2 N
v = 10 m/s

Formula:
P = F · v

Substitution:
P = 2 × 10 = 20 W

Answer: Power = 20 W

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Numerical Exam Tips

• Always write the formula before substitution.
• Use correct SI units.
• Show steps clearly to get partial marks.
• Underline the final answer.

“Step-wise solutions guarantee marks in numericals.”

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.

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📚 Complete Lesson Index (Part 1 – Part 39)

1. Part 1 – Introduction to Work
2. Part 2 – Types of Work
3. Part 3 – Variable Force & Graphs
4. Part 4 – Kinetic Energy
5. Part 5 – Work–Energy Theorem
6. Part 6 – Potential Energy
7. Part 7 – Conservative Forces
8. Part 8 – Mechanical Energy
9. Part 9 – Power
10. Part 10 – Power Applications
11. Part 11
12. Part 12
13. Part 13
14. Part 14
15. Part 15
16. Part 16
17. Part 17
18. Part 18
19. Part 19
20. Part 20
21. Part 21
22. Part 22
23. Part 23
24. Part 24
25. Part 25
26. Part 26
27. Part 27
28. Part 28
29. Part 29
30. Part 30
31. Part 31
32. Part 32
33. Part 33
34. Part 34
35. Part 35
36. Part 36
37. Part 37
38. Part 38
39. Part 39 – Final IIT Tough Problems & Solutions

Prepared by: Shaktimatha Learning 🌱

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