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The weightless strut in the figure below is not attached to the wall; it is prev

ID: 1975052 • Letter: T

Question

The weightless strut in the figure below is not attached to the wall; it is prevented from falling only by friction. (Let w = 450 N, L = 5.25 m and h = 2.85 m.)


(a) Find the magnitude of the force of friction between the wall and the strut.


(b) Find the normal force exerted by the wall on the strut.


(c) Find the minimum coefficient of static friction.

Explanation / Answer

let the tension in the rope be T and angle be ? friction force be F normal reaction be N d=sqrt( L^2-h^2 )/2=2.2 for balancing forces in horizontal direction , TCos? = N for balancing torque about center TSin? = F a)balancing forces in vertical direction we get , TSin? + F =W => T = w/2Sin? = w/2(h/L) => T = Lw/2h = 414.47 N b)N =Tcos? = Lw/2h * 2d/L = wd/h =347.36 N c) µN >= F => µ>= tan? = h/2d=0.6477 so min value of µ is h/2d