There are basically three types of Inertia-:
(a) Inertia of Rest: The inability of a body to change by itself its state of rest is known as Inertia of Rest.
(i) Person sitting in a car falls backwards, when the car suddenly starts. It is because the lower portion in contact with the car comes in motion where as the upper part tries to remain at rest due to inertia of rest.
(ii) When we shake the branch of a tree, the leave or the fruits falls down because the branches comes in motion where as the leaves or the fruit tends to remain at rest and hence gets detached.
(b) Inertia of Motion: The Inability of a body to change by itself its state of uniform motion is known as Inertia of motion.
(i) When a moving car suddenly stops the person sitting in the car falls forward because the lower portion of the body in contact with the car comes to rest whereas the upper part tends to remain in motion due to inertia of motion.
(ii) An athlete runs a certain distance before taking a long jump because the velocity acquired by running is added to the time of jump, so that it can cover a long distance.
(c) Inertia of Direction: The inability of a body to change by itself its direction of motion.
(i) When a car moves round a curve the person sitting inside is thrown outwards in order to maintain his direction of motion due to inertia of motion.