Topic 13: One-Page Revision Sheet

Chapter 2: Laws of Motion – One Page Revision

1. Force

Force is a push or pull which can change the state of rest, state of motion, speed, direction or shape of a body.

SI unit of force: newton (N)

2. Inertia

Inertia is the property of a body by which it resists any change in its state of rest or uniform motion.

Mass is the measure of inertia.

Types of Inertia

• Inertia of rest
• Inertia of motion
• Inertia of direction

3. Newton’s First Law of Motion

A body remains at rest or in uniform motion in a straight line unless acted upon by an external unbalanced force.

Also called the law of inertia.

4. Momentum

Momentum is the quantity of motion of a body.

Momentum (p) = m × v

SI unit: kg m s^-1

5. Newton’s Second Law of Motion

The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction of the force.

Formula: F = m × a

6. Impulse of Force

Impulse is the product of force and time.

Impulse = F × t = change in momentum

SI unit: N s

7. Newton’s Third Law of Motion

For every action, there is an equal and opposite reaction.

Action and reaction forces act on different bodies.

8. Law of Conservation of Momentum

If no external force acts on a system, the total momentum of the system remains constant.

m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

9. Important Applications

• Walking – action and reaction
• Swimming – push water backward
• Recoil of gun – momentum conservation
• Rocket propulsion – Newton’s third law
• Seat belts – inertia

10. CET Exam Focus

• Direct MCQs from laws statements
• Formula-based numericals (F = ma, p = mv)
• Impulse and momentum relation
• Action–reaction identification