why it is nessery to run along with a moving bus and in the same direction of bus, while alighting from it?

due to inertia. .our body is in rest in the  respect to  the bus the sudden change in condition of our body may cause in fall.. . when we alighting from bus, we need to run i the same direction of the bus to maintain our motion of the body. .

Due to inertia of motion your body will tend to be in the state of uniform motion even after you get down from the bus. however the moment your feet touches the ground your lower part of your body comes to rest and the upper part that is your head moves foward and  you fall down.to prevent this you run along the direction of bus and gradually come to rest.