See the attached drawing file.
The asking problem:
A block of weight W=60 lb rests on a rough plane as shown. Knowing that "alpha"= 20° and Us (coefficient of static friction) = 0.30, determine the magnitude and direction of the smallest force P required to start the block up the plane.
The answer of this problem for verification: 35.9 lb at 36.7° directed up and to the right.
Solution: Assume that the magnitude of the force is P, and direction is "theta" denoted by 'x'. Denote "alpha" by 'a', where a=20 degree=Pi/9. If the direction of the force P is up and right, then the direction of the friction force should parallel to the ...
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