Momentum

Introduction of momentum

Momentum is defined as the product of mass and velocity.

Momentum,  p  = m x v                                                              

            m – mass (kg)

            v – velocity ( ms^-1)

SI Unit:  is kg ms^-1. It can also be written as N s (Newton second)

Momentum is a vector quantity. The direction of momentum follows the direction of the velocity.

Principle of conservation of momentum

In any collision or interaction between two or more objects in an isolated system, the total momentum before collision is equal to the total momentum after collision.

m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

Three types of collisions 
1)   Elastic collision

      Both objects move separately after collision.

    - In an elastic collision, the kinetic energy is conserved. 

     

     Total Momentum Before collision = Total Momentum after collision

                                    m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

2)  Inelastic collision

     Both objects move together after collision.

    

    Total Momentum Before collision = Total Momentum after collision

                                  m₁u₁ + m₂u₂ = (m₁ + m₂) v

 3) Explosion

    Both objects are initially stationary, and move in opposite directions after the explosion. 

   
  

  
 Total Momentum Before collision = Total Momentum after collision
                                       (at rest) 0 = m₁v₁ + m₂v₂
                                             m₁v₁ = - m₂v₂

   * (-ve sign means opposite direction)

Application of Conservation of Momentum in Explosion 

  1. Fire a pistol or rifle
  2. Launching a rocket
  3. Application in jet engine
  4. Fan boat

MOMENTUM SONG