Chapter 7207(b)The work done by the escalator isWmgvte===power timeforce exerted speed timebgafafafwherethvnhs=+as above.Thus,Wmgvhhes=+.As a check, the total work done on the person’s body must add up to mgh, the work anelevator would do in lifting him.It does add up as follows:WWWmgnhhhmgvhhmgh nhvhmghesssss∑=+=+++=++=personP7.53(a)∆KmvW=−=∑1202, sovWm22=and vWm=2(b)WFdFWdxx=⋅=⇒ =Fd*P7.54During its whole motion from y=10 0. m to y320. mm, the force of gravity and the force of theplate do work on the ball. It starts and ends at rest
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