Chapter 10: Work and Energy Short Questions | science Class 9 CBSE

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Chapter 10: Work and Energy Short Questions | science Class 9 CBSE | ByteNotes.in

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Question 1

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Q1. Define work done in scientific terms.

Work is done when a force is applied and displacement occurs in the direction of the force.
Work = Force × Displacement.
No displacement → no work.

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Question 2

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Q2. State the SI unit of work.

The SI unit of work is joule (J).
1 joule = 1 newton × 1 metre.
Work is scalar.

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Question 3

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Q3. What is the condition for negative work?

When the force and displacement are in opposite directions.
Friction does negative work.
Work = F × s × cosθ; if θ = 180°, work is negative.

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Question 4

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Q4. Define energy.

Energy is the capacity to do work.
It is a scalar quantity.
SI unit is joule (J).

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Question 5

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Q5. What is kinetic energy?

Energy possessed by a body due to motion.
K.E. = ½mv².
Depends on mass and velocity.

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Question 6

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Q6. Give the expression for potential energy.

Potential energy = mgh.
Where m = mass, g = gravity, h = height.
Stored energy due to position.

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Question 7

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Q7. What is power?

Rate of doing work.
Power = Work / Time.
SI unit: watt (W).

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Question 8

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Q8. Define 1 watt.

If 1 joule of work is done in 1 second.
Then power = 1 watt.
1 W = 1 J/s.

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Question 9

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Q9. State the commercial unit of energy.

Kilowatt hour (kWh).
1 kWh = 1000 W × 3600 s = 3.6 × 10⁶ J.
Used in electricity bills.

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Question 10

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Q10. Define the law of conservation of energy.

Energy can neither be created nor destroyed.
It can only change from one form to another.
Total energy remains constant.

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Chapter sections

Chapter 10: Work and Energy | Short Questions

Q1. Define work done in scientific terms.

Q2. State the SI unit of work.

Q3. What is the condition for negative work?

Q4. Define energy.

Q5. What is kinetic energy?

Q6. Give the expression for potential energy.

Q7. What is power?

Q8. Define 1 watt.

Q9. State the commercial unit of energy.

Q10. Define the law of conservation of energy.