Question

A 2.0 kg object moving 5.0 m/s collides with and sticks to an 8.0 kg object initially at rest.

a). Calculate the total momentum of the system before the collision.

b). Calculate the total kinetic energy of the system before the collision.

c). Calculate the kinetic energy lost by the system as a result of this collision.

Answer 1

We have Momentum, and Kinetic Energy,  

Let, Mass of first body,    Mass of second body,

Initial Velocity of first body, Initial Velocity of second body,

Final Velocity of first body and second body ( both mass sticks together) ,   

a)

Total Momentum before collison

b)

Total Kinetic Energy before collision,

c)

According to law of conservation of momentum, Initial Momentum = Final Momentum   

Since both the masses are moving together after collision ,

Since the body is initially at rest,   

Final velocity,   

Substituting, , ,    

Total Kinetic Energy after collision,   

Substituting, , ,     

Kinetic Energy Lost = Initial Kinetic Energy - Final Kinetic Energy,