# Homework 5 - Homework 5 Homework5...

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2/7/2017Homework 51/24Homework 5Due: 8:00am on Wednesday, February 8, 2017You will receive no credit for items you complete after the assignment is due.Grading PolicyProblem 7.7The human small intestine moves food along its 6.9­length by means of peristalsis, a contraction and relaxation ofmuscles that propagate in a wave along the digestive tract.Part AIf the average force exerted by peristalsis is 0.18, how much work does the small intestine do to move food along itsentire length?Express your answer to two significant figures and include appropriate units.ANSWER:Correct± All Work and No PlayLearning Goal:To be able to calculate work done by a constant force directed at different angles relative to displacementIf an object undergoes displacement while being acted upon by a force (or several forces), it is said thatwork is being doneon the object. If the object is moving in a straight line and the displacement and the force are known, the work done by theforce can be calculated as,whereis the work done by forceon the object that undergoes displacementdirected at anglerelative to.Note that depending on the value of, the work done can be positive, negative, or zero.In this problem, you will practice calculating work done on an object moving in a straight line. The first series of questions isrelated to the accompanying figure.Part A1.2
2/7/2017Homework 52/24What can be said about the sign of the work done by the force?ANSWER:CorrectWhen, the cosine ofis zero, and therefore the work done is zero.Part BWhat can be said about the work done by force?ANSWER:CorrectWhen,is positive, and so the work done is positive.Part CThe work done by forceisANSWER:CorrectWhen,is negative, and so the work done is negative.Part DThe work done by forceisANSWER:It is positive.It is negative.It is zero.There is not enough information to answer the question.It is positive.It is negative.It is zero.positivenegativezero
2/7/2017Homework 53/24CorrectPart EThe work done by forceisANSWER:CorrectPart FThe work done by forceisANSWER:CorrectPart GThe work done by forceisANSWER:Correctpositivenegativezeropositivenegativezeropositivenegativezeropositivenegativezero
2/7/2017Homework 54/24In the next series of questions, you will use the formulato calculate the work done by various forces on an object that moves 160 meters to the right.Part HFind the workdone by the 18­newton force.
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