Question

why do you fall in forward direction when a moving bus brakes to stop and fall backward when it accelerates from rest

Answer 1

The tendency of the body to remain at rest or motion is judged by inertia
Inertia of motion:when a bus or train suddenly stops we tend to come forward our body is still in motion
Inertia of rest:When a bus or train starts to move from rest we tend to fall backwards because our upper body is in rest.

Answer 2

This is nothing but due to inertia.

Inertia means a body tends to remain in its state of rest or motion ...

When an external force is applied it changes its state of motion or rest

So now let's see this case,

case 1,

The brakes are applied

before the brakes were applied our body was at rest but our legs in direct contact with the bus were sharing its motion . So when brakes were applied our legs stop due to inertia while the body moves aheadd. Hence we fall in forward directdirection

Case 2,

When bus acclerates,

similarly this time the bus was at rest and so the legs . When the bus is accelerated our legs move ahead with the bus being in close contact but our body remains behind . thus we fall backward. 

I hope u understood. 

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