(33%) Problem 3: A block is resting on a wooden plank. There is a hinge OL end o

Question

(33%) Problem 3: A block is resting on a wooden plank. There is a hinge OL end of the plank which allows the other end to be lifted to create an angle, 6, with respect to the horizontal as shown in the figure The coefficient of static friction between the block and the plank is Hs- Otheexpertta.com 3%Part (a) Please select the correct Free Body Diagram, where Fe isthe force due to gravity, FN is the normal force, and is the static friction force. Grade Summary Potential 80% Attempts remaining: 4 per attempt) Feedback: deduction per feedback Hints: deduction per hint. Hints remaining

Explanation / Answer

part a:

forces acting on the block are:

Fg --> force due to gravity, acting vertically downward

Fn --> normal force, perpendicular to the plank surface

Fs-> static friction force, opposing the sliding of the block

hence acting along the plank, in upwards direction

so 5th option (2nd row, middle option) is the correct one.

part b:

the block will begin to move just when

the friction force balances the component of weight along the plank

component of weight along the plank=m*g*sin(theta)

friction force=mu*normal force

=mu*m*g*cos(theta)

so the block will begin to move,

when mu*m*g*cos(theta)=m*g*sin(theta)

==>tan (theta)=mu

==>theta=arctan(mu)...(ans)

part c:

coefficient of static friction=tan(theta)

=tan(25)=0.4663

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