\"The correct solution is only valid for a certain range of angles theta (see di
ID: 1291608 • Letter: #
Question
"The correct solution is only valid for a certain range of angles theta (see diagram). Write up an explanation of why the solution is only valid for certain angles, and which range of angles will allow the system to remain in static equilibrium."
Please help me with this problem. I've been staring at it and cannot figure out where to start or why it would only be valid for certain angles. Thanks
PROBLEM 1 [4 pts] A uniform disk of mass M and radius R rests against a vertical wall and is held in place by two light cords that make angles theta with the wall. As shown below, the cords are attached to the disk a horizontal distance of 2/3R from the disk center. (Only one cord is visible in the figure. The second cord is directly behind the first on the back side of the disk.) (a) Find the tensions in the cords, and the horizontal and vertical components of the force exerted on the disk by the wall at the point of its contact with the disk. (b) What is the minimum coefficient of static friction between the wall and the disk for the system to remain in equilibrium?Explanation / Answer
Fn should be +ve hence (3/5)mgtan(theta)>=0
hence we get tan(theta)>=0
or theta>=0----(i)
also for equilibrium tension should not be 0.And it should be positive otherwise string would become slack.
Hence it is valid for certain angles
and hence no equlibrium.
hence FT>0
or (3mg)/(10cos(theta))>0
hence cos(theta)>0
hence theta<90o---(ii)
combining (i) and (ii)
we get 0o<=theta<90o
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