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on September 18, 2020
Elastic collision
Elastic collision is a type of collision in which both energy and momentum are conserved.
There is no loss of energy , neither loss of momentum in elastic collision.
Example of elastic collision are ;
- A ball that bounces off the ground back to the original height.
- Molecules of gases in a container , hit the wall of the container and bounces back.
The momentum and kinetic energy remain the same after the collision.
Momentum = mass x velocity
MV + mv = MU + mu = constant
where V ,v and U, u are the initial and final velocities respectively. For an Elastic collision the momentum is conserved
If a ball bounces back from the ground
Total moment before collision= MV + mv= M x 0 + m x v= mv where the initial velocity of the ground=0
Total momentum after collision = MU + mu= M X0 + m x u = mu
Hence mv =mu, v=u
The Total kinetic energy before collision = and after collision , the total kinetic energy = , hence,
v=u
Inelastic collision
Inelastic collision is a type of collision in which only the momentum is conserved.
There is loss of energy in inelastic collision.
Example of inelastic collision are ;
- A lorry and a car that collide with each other.
- An aeroplane that crashes to the ground.
The momentum remain the same after the collision, but there is loss of kinetic energy.
The momentum before collision = MV + mv
The momentum after collision = MU + mu
MV + mv = MU + mu . if they move together after collision with common velocity u
Then
MV + mv = (M + m)u
where V ,v and U, u are the initial and final velocities respectively. For an inelastic collision the momentum is conserved but the K.E is not.
because U and u are less than V and v respectively
if they move together and have common velocity u after collision, then
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