Question

Conceptual Questions and Exercises 75 You get into an elevator in the lobby on the ground floor and hit the button for the 10th floor. What is the dired- tion of your acceleration right after the elevator starts moving and right before it stops at the 10th floor? 22.

Answer 1

Right after the elevator starts moving, the acceleration is upward as the net acceleration should be upward in order to counter the acceleration due to gravity. But the acceleration has to decrease otherwise the elevator will keep moving upward and finally escape the earth.

That is why, the acceleration becomes zero for some time in between such that you move with constant velocity. And as soon as you are about to reach the 10^th floor, you need to further decrease the velocity to zero. So, you will need to decelerate in last part of the journey. Hence, you will have a downward acceleration as you reach the 10^th floor and finally come to rest.

However, the pseudo force will work in opposite direction at both the points. So, you will experience a downward acceleration at the start and an upward acceleration at the end.