Class 9 Physics Chapter 5 – Work, Energy and Power is an important chapter in mechanics. In this chapter, students learn how work is done by a force, different forms of energy, the law of conservation of energy, and the concept of power.
These notes are prepared according to the 2026 Punjab Board syllabus and are helpful for exam preparation, revision, and conceptual understanding.
Students can download the complete chapter notes in PDF format, which include definitions, formulas, solved questions, MCQs, short questions, and important long questions.
Topics Covered in Chapter 5 – Work, Energy and Power
These notes cover all important topics of the chapter, including:
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Work and conditions for work done
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Positive work, negative work, and zero work
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Energy and different forms of energy
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Kinetic energy
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Potential energy
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Law of conservation of energy
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Power and its units
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Efficiency of machines
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Renewable and non-renewable energy sources
Class 9 Physics Chapter 5 MCQs
1. A joule can also be written as:
(a) kg m s⁻²
(b) kg m s⁻¹
(c) kg m² s⁻³
(d) kg m² s⁻² ✅
2. The SI unit of power is:
(a) joule
(b) newton
(c) watt ✅
(d) second
3. Which of the following is not a renewable energy source?
(a) Hydroelectric energy
(b) Fossil fuels ✅
(c) Wind energy
(d) Solar energy
4. What is the SI unit of work?
(a) Newton
(b) Watt
(c) Joule ✅
(d) Pascal
5. What is potential energy?
(a) Energy due to motion
(b) Energy due to position ✅
(c) Energy due to temperature
(d) Energy due to power
6. Tidal energy is obtained from:
(a) Heat of Sun
(b) Sea waves
(c) Rise and fall of sea water ✅
(d) Chemical reactions
7. Power is defined as:
(a) Work done × Time
(b) Work done ÷ Time ✅
(c) Energy × Distance
(d) Force × Velocity
Short Questions – Class 9 Physics Chapter 5
1. Define Work and its SI Unit:
Work:
Work is said to be done when a force applied on an object causes it to move in the direction of the force.
Formula:
W=F×d
Where:
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W = Work done
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F = Force applied
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d = Displacement of the object in the direction of force
2. Differentiate between Renewable and Non-Renewable Energy Sources
Renewable Energy Sources:
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These sources can be naturally replenished after use.
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They are available in unlimited quantity.
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They cause little or no pollution.
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Examples: Solar energy, wind energy, hydroelectricity, tidal energy, geothermal energy.
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They are sustainable and environment-friendly.
Non-Renewable Energy Sources:
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These sources cannot be replenished once they are used.
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They are limited in quantity and will eventually run out.
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They cause pollution and contribute to global warming.
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Examples: Fossil fuels (coal, oil, natural gas) and nuclear fuels.
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They are not sustainable for long-term use.
3. What is Potential Energy?
Definition:
Potential energy is the energy possessed by a body due to its position or shape. It is a form of stored energy that can be used to do work.
Examples:
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Gravitational potential energy: Water at a height possesses energy due to its position.
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Elastic potential energy: A stretched or compressed spring possesses energy due to its shape.
Formula for Gravitational Potential Energy:
- Ep=mgh
📥 Download Chapter 5 Notes – Work, Energy and Power
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Why These Notes Are Helpful
These notes help students:
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Understand work, energy, and power concepts easily
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Prepare for board examinations
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Revise the chapter quickly before exams
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Practice important exam questions
The notes follow the latest Punjab Board syllabus, making them reliable for students preparing for annual examinations.