Key Notes:

Definition of Momentum

Momentum is defined as the product of an object’s mass and its velocity.

• Formula: p = m × v
• p = momentum
• m = mass
• v = velocity

Law of Conservation of Momentum

• States that in a closed system, the total momentum remains constant if no external forces act on it.
• This means the total momentum before an event (collision or explosion) is equal to the total momentum after the event.

Mathematical Expression

For two objects in a system:

• Before collision: _ptotal = p1+p2
• After collision: _p′total = p′1+p′2
• If no external forces: _ptotal = p′total

Types of Collisions

• Elastic Collision: Both momentum and kinetic energy are conserved. Objects bounce off each other.

• Inelastic Collision: Momentum is conserved, but kinetic energy is not. Objects may stick together or deform.

Real-World Examples

Billiard Balls: When balls collide, momentum is transferred from one ball to another, but the total momentum of the system is conserved.

Recoil of a Gun: When a bullet is fired, the momentum of the bullet and the gun is equal and opposite, conserving the total momentum of the system.

Implications and Applications

• Understanding momentum conservation helps in analyzing collisions in sports, vehicle accidents, and space missions.
• Used in designing safety features like airbags and crumple zones in cars.

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