There are two types of collision namely elastic and inelastic.

### Elastic Collision:

For elastic collision, the total momentum is conserved and the kinetic energyEnergy is the ability to do work. Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, and electrical energy. Units of Energy: The SI unit... More is also conserved.

Let us put into consideration two masses m_{1 }and m_{2} moving with initial velocities u_{1 }and u_{2} before collision and with final velocities v_{1 }and v_{2} in the same direction after collision.

For a perfectly elastic collision, we can write an equation from the law of conservation of momentum and the law of conservation of kinetic energy.

The total momentum before and after collision:

m_{1}U_{1 }+m_{2}U_{2} = m_{1}V_{1 }+m_{2}V_{2}

The kinetic energy before and after is

\(\scriptsize \frac{1}{2}m_1u_1^2 + \frac{1}{2}m_2u_2^2 = \frac{1}{2}m_1v_1^2 + \frac{1}{2}m_2v_2^2 \)### Inelastic Collision:

In an inelastic collision, the total momentum is conserved but the kinetic energy varies i.e. is not conserved. This occurs when two colliding bodies stick together after collision and move with a common velocity.

m_{1}U_{1 }+ m_{2}U_{2} = (m_{1}+m_{2})V

K.e = \(\scriptsize \frac{1}{2}m_1u_1^2 + \frac{1}{2}m_2u_2^2 = \frac{1}{2}(m_1 + m_2)V^2 \)

For a completely inelastic collision, the kinetic energy before collision is greater than the kinetic energy after collision.

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