volume_mute

Holding the bricks, any force exerted?

publish date: 2023/06/27 02:24:00 GMT+10

volume_mute

Work definition corresponds to our everyday meaning of the word in that when you lift a brick 6 feet from the floor you do twice as much work as when you lift it 3 feet. Or suppose you lift 50 bricks to a height of 3 feet. You do 50 times as much work as lifting one brick that high.

But here comes a conclusion that may seem odd.  After you lift a dozen bricks up to your waist, you are told by your boss to hold them there for 5 minutes.  Do you do work in holding them there?  To answer this, we must go back to our definition.  The force you exert is simply the weight of the 50 bricks.

  1. In holding them waist-high, does the force move the bricks through a distance?
  2. Using the formula, calculate the total work done in holding the bricks.

Formula: W = Fd

Please drag and drop the selected option in the right place or type it instead
no
yes
0
50

Correct Answer

(1) no
(2) 0

Explanation

There is motion within the muscles in holding the bricks, so work is done inside your body, but no external work is done on the bricks.  it is this external work with which we are concerned.

Reference

Basic Physics: A Self-Teaching Guide

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