Explain why, a person travelling in a bus falls forward when the bus stops suddenly.

When moving bus suddenly stops, the passengers sitting or standing in the bus are thrown forward. This is due to inertia of motion and can be explained as follows: when the moving bus suddenly stops, the lower part of the body of the passenger contact with the bus suddenly comes to rest while the upper part of the body tends to retain its state of motion due to inertia. As a result, the passenger is thrown forward.