Question

What is the main difference between inelastic collision and a perfectly inelastic collision?

Answer 1

Hint: Collision of two or more bodies occur when they collide with each other after moving with some velocity. Their velocity after collision may or may not change depending on the type of collision. Two major types of collision are elastic collision and inelastic collision depending on whether the kinetic energy is conserved or not.

Complete answer:
When two bodies collide with each other in different systems, different scenarios can occur.
During collision of two bodies, when the kinetic energy of the system is not conserved, the collision is said to be inelastic collision. Sometimes the kinetic energy of the bodies is lost due to the friction between the bodies and hence the kinetic energy is converted to vibrational. The final kinetic energy of the bodies may increase or decrease after inelastic collision.
In a perfectly inelastic collision of two bodies, the maximum kinetic energy is lost. In this case, the lost energy acts as bonding energy between the bodies of the system and hence, they stick together after collision.
Therefore, in inelastic collision, the kinetic energy is not conserved whereas in a perfectly inelastic collision, maximum kinetic energy is lost and the bodies stick together.

Note:
Coefficient of restitution is the ratio of relative velocity before collision to the relative velocity after collision. In inelastic collision, the value of coefficient of restitution lies between zero and one whereas for perfectly inelastic collision, the value of coefficient of restitution is zero. The collision in which the kinetic energy of the system is conserved is called elastic collision. The bodies undergo deformation in inelastic collision.