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n Dite TOT9P2017 1P2E00:00 AM-Due Date: 11/3/2017 11:59:00 PM End Date: 11/3/201

ID: 1774770 • Letter: N

Question

n Dite TOT9P2017 1P2E00:00 AM-Due Date: 11/3/2017 11:59:00 PM End Date: 11/3/2017 11:59:00 PM (10% ) Problem 4: Consider a rigid steel beam of length L-145 m and mass mb-470 kg resting on two supports, one at each end. A worker of mass mw- 61 kg sits on the beam at a distance x from support A. Refer to the figure. an 33% Part (a) Enter an expression for the force support B must exert on the beam in order for it to remain at rest, in terms of defined uantities and & leted 33 the beam in order for it to remain at rest. Use g with three significant figures % Part (b) when the worker sits at a distance x = 4S m from support A, calculate the force, in newtons, that support B must exert on eted eted FB Grade Summary Potential Submissions 100% eted coso 4 5 6 cotan asin acoso atano) acotanO sinh0 cosho cotanho °Degrees Radians Attempts remaining 1o ( per attemp) detailed view eted Submit Hine Hints-%. deduction per hint. Hints remaining:- Feedback: doluction per feedback -- 33% Part (c) The force exerted on the beam by support A is measured and found to be FA-1950 N. At what distance x, in meters, from support A is the worker sitting now

Explanation / Answer

(A) balancing moment about A,

M = (L/2 mb g ) + (mw g x ) - (L FB) = 0


Fb = g (mb/2 + mw(x/L))

(b) Fb = 9.81(235 + 18.9) = 2491 N


(C) in vertical,

FA + FB = (470 + 61) (9.81)

FB = 3259.1 N


3259 / 9.81 = 235 + 61 (x / 14.5)

x = 23 m