When a train stops suddenly, passengers in the running train feel an instant jerk in the forward direction because A. The back of the seat suddenly pushes the passengers forward B. Inertia of rest stops the train and takes the body forward C. Upper part of the body continues to be in the state of mention whereas the lower part of the body in contact with seat remains at rest D. Nothing can be said due to insufficient data
Hint: The resistance of any physical entity to any change in velocity is known as inertia. Changes in the object's speed or direction of motion are included. The tendency of things to keep moving in a straight line at a constant pace while no forces act on them is an example of this property.
Complete answer: Inertia is a property of an entity that resists some force that tries to move it or change the magnitude or direction of its motion if it is already moving.
A. The back of the seat does not push the passengers forward. Rather it is caused by the inertia of motion. Hence this is not the correct answer. B. In this situation, the inertia of rest is not involved, but the inertia of motion is involved.Hence this option is not correct. C. This is caused due to inertia of motion. When a speeding bus comes to an abrupt halt, the lower body comes to a complete stop, while the upper body continues to move in a uniform motion. As a result, the passengers are pushed forward. Hence this is the correct answer. D. This option is not correct as it has sufficient data.
Therefore, the correct option is C.
Note: The law of inertia, also known as Newton's first law, states that if a body is at rest or travelling in a straight line at a constant speed, it will continue to be at rest or continue to move in a straight line at a constant speed until it is acted upon by force.