Laws of motion

1. Laws of Motion
• An overview of Newton's Three Laws of
Motion
• Class 11 Physics

2. Introduction
• Motion is the change in position of an object
with respect to time.
• Newton formulated three fundamental laws to
explain motion.

3. Force and Motion
• Force is a push or pull that changes or tends to
change the state of motion of an object.

4. Newton’s First Law
• Also called the Law of Inertia.
• An object remains at rest or in uniform motion
in a straight line unless acted upon by an
external force.

5. Examples of First Law
• 1. A passenger jerks forward when a car
suddenly stops.
• 2. A book remains at rest on a table until
pushed.

6. Newton’s Second Law
• The rate of change of momentum of an object
is directly proportional to the applied force
and takes place in the direction of the force.
• F = ma

7. Applications of Second Law
• 1. Pushing a heavier object requires more
force.
• 2. Kicking a football – the greater the force,
the greater the acceleration.

8. Newton’s Third Law
• For every action, there is an equal and
opposite reaction.

9. Examples of Third Law
• 1. A gun recoils when fired.
• 2. A rocket moves upward due to downward
expulsion of gases.

10. Momentum
• Momentum = mass × velocity.
• It is a measure of the quantity of motion of a
body.

11. Conservation of Momentum
• In the absence of external forces, the total
momentum of a system remains constant.

12. Applications of Conservation of
Momentum
• 1. Firing of a bullet from a gun.
• 2. Recoil of a cannon.
• 3. Motion of rockets.

13. Balanced and Unbalanced Forces
• Balanced forces do not change the state of
motion.
• Unbalanced forces cause acceleration.

14. Friction and Motion
• Friction is a force that opposes motion
between two surfaces in contact.
• It plays an important role in walking, driving,
and stopping vehicles.

15. Summary
• Newton’s Three Laws form the foundation of
classical mechanics.
• They explain the relationship between force,
mass, and motion.