Page 1: Introduction
Force: Push or pull that can change state of motion or shape.
Effects: start/stop motion, change speed/direction, change shape.
This chapter covers Galileo’s ideas, inertia, Newton’s three laws, momentum, and conservation.
Page 2: Balanced and Unbalanced Forces
- Balanced: Net force zero → no change in motion.
- Unbalanced: Net force non-zero → acceleration.
Example: Tug of war.
Page 3: Inertia
Tendency of body to resist change in state of motion.
Types: inertia of rest, motion, direction.
Mass measures inertia.
Page 4: Newton’s First Law of Motion
Also called Law of Inertia.
Galileo’s idea of natural motion.
Page 5: Newton’s Second Law of Motion
F = ma (derived)
1 Newton = force giving 1 kg mass acceleration 1 m/s²
Page 6: Momentum
Second law: F = Δp / Δt
Unit: kg m/s
Page 7: Newton’s Third Law of Motion
Action and reaction act on different bodies.
Example: swimming, rocket propulsion.
Page 8: Conservation of Momentum
If no external force, total momentum before = total momentum after.
Derived from third law.
Used in collisions, recoil.
Page 9: Examples of Laws
Second: Cricket ball hit hard → large acceleration.
Third: Gun recoil.
Page 10: Key Formulas
- F = ma
- p = mv
- F = Δp / Δt
- m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂ (conservation)
Page 11: Practice Questions - Easy (1-10)
- State Newton’s first law.
- Define inertia.
- Unit of force.
- Momentum formula.
- Action-reaction pair example.
- Balanced force effect.
- Third law application in walking.
- 1 N definition.
- Recoil example.
- Conservation of momentum condition.
Page 12: Practice Questions - Medium (11-20)
- Force on 2 kg mass for acceleration 5 m/s².
- Momentum of 10 kg body at 4 m/s.
- Explain inertia of direction.
- Find change in momentum.
- Recoil velocity of gun numerical.
- Collision conservation example.
- Why seat belt needed (first law).
- Force = rate of change of momentum.
- Third law in rocket.
- Mass vs inertia.
Page 13: Practice Questions - Hard (21-30)
- Two body collision detailed.
- Prove conservation from third law.
- Advanced recoil with numbers.
- Multiple force numerical.
- Explain all inertia types with examples.
- Derive F=ma from second law.
- Real-life third law applications.
- Conservation in explosion.
- Force-time graph area.
- Mathematical proof of laws.
Page 14: NCERT Exercise Types
Numerical on F=ma, momentum, conservation, reasoning questions.
Page 15: Laws Summary
All three laws with statements and examples.
Page 16: Common Mistakes
- Thinking action-reaction on same body
- Wrong sign in velocity
- Forgetting mass in momentum
- Confusing first and second law
- Not using conservation properly
Page 17: Previous Year Questions
State laws, numerical on momentum, recoil, conservation.
Page 18: Exam Tips
- Quote laws exactly
- Draw free body diagrams
- Show before-after in conservation
- Use vector arrows
- Practice numerical daily
Page 19: Quick Revision Sheet
All laws, formulas, examples.
Page 20: Real-Life Examples
Seat belt, rocket, walking, sports.
Page 21: Final Motivation
Chapter 9 complete! Newton’s laws are foundation of Physics.
Master numerical and examples.
Board Buddy Physics is unstoppable 🦖
Page 22: Extra Numericals
More solved problems.
Page 23: Inertia Examples
All types detailed.
Page 24: Conservation Proof
Step-by-step derivation.
Page 25: Third Law Applications
Rocket, swimming, bird flying.
Page 26: Formula Table
All important equations.
Page 27: Thank You & Copyright
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