Question

Ain't the net acceleration upwards when the lift is going up and deccelerating? or in other case Ain't the net acceleration downwards when the lift is going down and deccelerating? Then why do we feel our weight less and more respectively in the above cases? ( should not it be when the acc is up weight should be felt more than true weight and vice versa)

Answer 1

Consider the normal force acting on you from the elevator:

• N = mg if the elevator is at rest or moving at constant velocity
• N = mg + ma if the elevator has an upward acceleration
• N = mg - ma if the elevator has a downward acceleration

The normal force is equal to your apparent weight. So, you actually feel a little heavier than usual when the elevator accelerates upward, and lighter than usual when the acceleration is down.

If lift is moving up with deceleration, the acceleration will be downwards.Because in this case, the elevator and the person are initially moving upward at a constant speed and slowing down to rest at a higher floor. The acceleration of the elevator is downward (opposite to the upward motion, which causes a reduction of the velocity).
N = mg - ma if the elevator has a downward acceleration.And when g=a , N=0 and we feel weight less.


If lift is moving down and decelerating,the accelration will be upward.
Beacuse in this case, the elevator and the person are initially moving downward at a constant speed and then slow to rest at a lower floor. The elevator accelerates upward (opposite direction to negative/downward velocity to reduce velocity magnitude).
N = mg + ma if the elevator has an upward acceleration.
So the person feel more weight in this case.