Lesson 5 – Work, Energy and Power Short Questions & Answers
Q1. What is work? Write its mathematical expression.
Work is said to be done when a force acting on a body produces displacement
in the direction of the force.
Mathematically, Work = F s cosθ
Q2. What is zero work? Give an example.
Work is zero when force acts on a body but no displacement occurs in the
direction of force.
Example: Centripetal force in circular motion.
Q3. Define energy.
Energy is the capacity of a body to do work.
Q4. What is kinetic energy?
The energy possessed by a body due to its motion is called kinetic energy.
Q5. Write the formula for kinetic energy.
Kinetic Energy = ½ mv²
Q6. What is work–energy theorem?
The work–energy theorem states that the work done by the net force acting on a body is equal to the change in its kinetic energy.
Q7. What is power?
Power is defined as the rate of doing work or the rate of transfer of energy.
Q8. Write the expression for power.
Power = Work / Time
Q9. Write the SI unit of power.
The SI unit of power is watt (W).
Q10. What is positive work?
Work is said to be positive when force and displacement are in the same direction.
Q11. What is negative work?
Work is said to be negative when force and displacement are in opposite directions.
Q12. Give one example of negative work.
Work done by friction on a moving body is negative.
Q13. Why is work done by centripetal force zero?
Centripetal force acts perpendicular to displacement, hence work done is zero.
Q14. What is instantaneous power?
Instantaneous power is the power at a particular instant and is given by P = F · v
Q15. State one difference between work and energy.
Work is the transfer of energy, whereas energy is the capacity to do work.
Exam Tip
- Write answers in 2–3 lines only.
- Do not over-explain.
- Use exact textbook language.
- Underline keywords for better impression.
“Short answers score full marks when written precisely.”
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
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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