You are holding a briefcase by the handle, with your arm straight down by your side.?

Does the force your hand exerts do work on the briefcase when (a) you walk at a constant speed on a horizontal floor and (b) you ride in an escalator from the first to second floor of a building? Explain.

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  • 3 weeks ago

    a) There is no work done, because you are moving in a horizontal direction; while the force of the briefcase weight is in a vertical direction, thus the angle between the force and the direction is 90 degrees; therefor the net work is therefor zero.

    b) In this case, the motion is along the direction of the weight of the briefcase, therefor there is a non-zero work as you the elevator moves from the first to second floor.

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