You open a restaurant and hope to entice customers by hanging out a sign (see th

Question

You open a restaurant and hope to entice customers by hanging out a sign (see the figure (Figure 1) ). The uniform horizontal beam supporting the sign is 1.60 m long, has a mass of 19.0 kg , and is hinged to the wall. The sign itself is uniform with a mass of 35.0 kg and over-all length of 1.20 m . The two wires supporting the sign are each 27.0 cm long, are 90.0 cm apart, and are equally spaced from the middle of the sign. The cable supporting the beam is 2.10 m long.

Part A

What minimum tension must your cable be able to support without having your sign come crashing down? Ans in N

Part B

What minimum vertical force must the hinge be able to support without pulling out of the wall? Ans in N

Need help solving this. Thanks in advance.

Explanation / Answer

A) balancing torque about hinge

T *(sqrt(2.1^2-1.6^2))/2.1*1.6 = 0.5*35*9.8*1.6+0.5*35*9.8*0.7+19*9.8*0.8

T = ( 0.5*35*9.8*1.6+0.5*35*9.8*0.7+19*9.8*0.8)/[(sqrt(2.1^2-1.6^2))/2.1*1.6]

= 524.4 N answer

B) F = 9.8*(19+35) - 524.4*sqrt(2.1^2-1.6^2) /2.1

= 189.6 N answer

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