Chapter 8: Force and Laws of Motion Short Questions | science Class 9 CBSE

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Chapter 8: Force and Laws of Motion Short Questions | science Class 9 CBSE | ByteNotes.in

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Question 1

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Q1. What is force?

A push or pull acting on an object.
It can change an object's motion or shape.
Measured in newtons (N).

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Question 2

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Q2. Define inertia.

Property of an object to resist change in its state of motion.
Heavier objects have more inertia.
Depends on mass.

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Question 3

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Q3. Write SI unit of force.

The SI unit is newton (N).
1 N = 1 kg·m/s².
It is a derived unit.

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Question 4

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Q4. What is momentum?

Product of mass and velocity.
It is a vector quantity.
SI unit is kg·m/s.

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Question 5

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Q5. Write Newton’s Second Law of Motion.

Force = mass × acceleration.
F = ma.
It explains relation between force and motion.

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Question 6

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Q6. Write Newton’s Third Law of Motion.

For every action, there is an equal and opposite reaction.
Forces act on different objects.
Examples: jumping, walking, firing gun.

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Question 7

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Q7. State the relation between force and momentum.

F = (mv - mu)/t.
Force equals rate of change of momentum.
Derived from second law.

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Question 8

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Q8. What are balanced forces?

Equal and opposite forces acting on an object.
No change in motion occurs.
Example: object at rest stays at rest.

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Question 9

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Q9. What is unbalanced force?

Unequal or unopposed force.
Causes change in motion or acceleration.
Example: pushing a box causing it to move.

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Question 10

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Q10. What is meant by recoil of a gun?

Backward movement of gun after firing a bullet.
Due to action-reaction force.
Explained by third law of motion.

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Chapter sections

Chapter 8: Force and Laws of Motion | Short Questions

Q1. What is force?

Q2. Define inertia.

Q3. Write SI unit of force.

Q4. What is momentum?

Q5. Write Newton’s Second Law of Motion.

Q6. Write Newton’s Third Law of Motion.

Q7. State the relation between force and momentum.

Q8. What are balanced forces?

Q9. What is unbalanced force?

Q10. What is meant by recoil of a gun?