Problem 509 | Friction

Problem 509
The blocks shown in Fig. P-509 are connected by flexible, inextensible cords passing over frictionless pulleys. At A the coefficients of friction are μs = 0.30 and μk = 0.20 while at B they are μs = 0.40 and μk = 0.30. Compute the magnitude and direction of the friction force acting on each block.
 

Two blocks on two inclined planes connected by cords

 

Problem 507 | Friction

Problem 507
The 2225-N block shown in Fig. P-507 is in contact with 45° incline. The coefficient of static friction is 0.25. Compute the value of the horizontal force P necessary to (a) just start the block up the incline or (b) just prevent motion down the incline. (c) If P = 1780 N, what is the amount and direction of the friction force?
 

Block on an incline pushed by horizontal force