HW 2 Begin Date: 8/29/2017 00 AM-Due Date: 9/7/2017 11:59 00 PM End Date: 9/7/20
ID: 1652462 • Letter: H
Question
HW 2 Begin Date: 8/29/2017 00 AM-Due Date: 9/7/2017 11:59 00 PM End Date: 9/7/2017 11-59 00 PM (7%) Problem 13: A block with a mass of, 1,5 kg rests on a wooden plank The the board is attached to a hinge so that the other end can be lifted forming an angle, with respect to the ground. Assume the x-axis is along the plank as shown in the Randomized Variables /4 = 0.44 normal force. Assume the block is at rest. Sg 17% Part (c) Write an expression for the magnitude of the maximum fraction force along the surface, F, in terms of given quantities and Dedahaons 96% Potential Subasissions Ateapts remaining mpleted sin(p) 1 2 3 per attempt) rtial Hints: 2 deductice per hint Hints remaining: ompleted es available in only the given parameters and the palette, for the sum of the forces along the plank, , for the maximum angle, 6 that the board can make with respect to the horizostal before the block 17% Part (e) write an e starts moving. (Write a 17% Part (0 Solve mmencally for the matimum angle, a-in degrees in terms of the given parameters and variables available in the palette.)Explanation / Answer
given m = 1.5 kg
coefficient of static friction mus = 0.44
angle with ground = theta
b. y direction component of gravity = -mg*cos(theta) [ -ve sign as its along -ve y axis]
c. Maximum friction force can be F
then F = mg*sin(theta)
d. along the plank
F - mg*sin(theta) = 0
e. But we know F = mus*N
where N = mg*cos(theta)
so, F = mu*mg*cos(theta)
mu*mg*cos(theta) = mg*sin(trheta)
tan(theta) = mu
theta = arctan(mu)
f. theta = arctan(0.44) = 23.749 deg
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