SEE DIAGRAM BELOW! You are in a glass elevator traveling upward with constant sp

Question

SEE DIAGRAM BELOW! You are in a glass elevator traveling upward with constant speed. You lift a box from the elevator floor up to your waist. The elevator moves a distance d during this time. From your point of view, you have done work = mgh where h = the height of your waist from the elevator floor. But a stationary observer outside the elevator sees the box move through a distance h + d since the elevator move a distance d while you lifted it. The stationary observer claims the work done is mg(h+d). Is this a contradiction or not? What is the source of the extra mgd work claimed by the stationary observer?

Explanation / Answer

Here the workdone by the person on box = m*g*h

the workdone by elevator on the box = m*g*d

so, total workdone on the box = m*g*d + m*g*h

= m*g*(d+h)

the source of extra energy is the elevator.

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