A passennger on a bus moving with uniform velocity lurches forward when the bus stops suddenly. Explain.?

Due to inertia of motion of the upper part of the body of passenger.

Explanation:

Passenger on a moving bus with uniform velocity lurches forward when the bus stops suddenly because when the bus was in uniform motion his body was in the state of inertia of uniform motion and when the brakes are applied suddenly to stop it still continues to be in motion while the bus stops within a fraction of seconds hence the passenger leans forward.

The lower part of the body of the passenger is in proper contact with the rigid seat of the bus structure but the upper part is loosely supported and when the brakes are applied the lower part of the body comes to rest along with the bus but the upper part feels the motion for a longer time duration and the passenger leans forward.