CHAPTER VII FRICTION 1- The block brake conit of a pin-connected lever and friction block at B. The coefficient of tatic friction between the wheel and the lever i and a torque of i applied to the wheel. Determine if the brake can hold the wheel tationary when the force applied to the lever i (a) P = 30 N, (b) P = 70 N. ((a) P = 30 N < 39.8 No, b) P = 70 N > 39.8 N Ye) 2- If a torque of M=300 N.m i applied to the flywheel, determine the force that mut be developed in the hydraulic cylinder CD to prevent the flywheel from rotating. The coefficient of tatic friction between the friction pad at B and the flywheel =0.4. (FCD = 3050 N = 3.05 kn)
3- The cam i ubjected to a couple moment of 5 N.m Determine the minimum force P that hould be applied to the follower in order to hold the cam in the poition hown. The coefficient of tatic friction between the cam and the follower i = 0.4. The guide at A i mooth.
4- The 5-kg cylinder i upended from two equal-length cord. The end of each cord i attached to a ring of negligible ma that pae along a horizontal haft. If the ring can be eparated by the greatet ditance d=400 mm and till upport the cylinder, determine the coefficient of tatic friction between each ring and the haft. (0.354) 5- A 35-kg dik ret on an inclined urface for which =0.3. Determine the maximum vertical force P that may be applied to link AB without cauing the dik to lip at C. (P = 371.4 N)
6- If =30 0 determine the minimum coefficient of tatic friction at A and B o that equilibrium of the upporting frame i maintained regardle of the ma of the cylinder C. Neglect the ma of the rod. (0.577) 7- The coefficient of tatic friction between the 150-kg crate and the ground i =0.3, while the coefficient of tatic friction between the 80-kg man hoe and the ground i =0.4.Determine if the man can move the crate.
8- The pool of wire having a ma M ret on the ground at A and againt the wall at B. Determine the force acting on the pool at A and B for the given force P. The coefficient of tatic friction between the pool and the ground at point A i. The wall at B i mooth. Given: P= 800 N a= 0.45 m, M= 150 kg b= 0.25 m, =0.35. (FA= 444 N < FAmax= 515 N) 9- The beam AB ha a negligible ma and thickne and i ubjected to a triangular ditributed loading. It i upported at one end by a pin and at the other end by a pot having a ma of 50 kg and negligible thickne. Determine the minimum force P
needed to move the pot. The coefficient of tatic friction at B and C are and =0.2 repectively. C B =0.4 (P = 355 N) 10- Determine the greatet angle o that the ladder doe not lip when it upport the 75-kg man in the poition hown. The urface i rather lippery, where the coefficient of tatic friction at A and B i. =0.3 (33.4 )
11- Determine the larget angle that will caue the wedge to be elf-locking regardle of the magnitude of horizontal force P applied to the block. The coefficient of tatic friction between the wedge and the block i =0.3. Neglect the weight of the wedge. (33.4 o ) 12- Determine the minimum applied force P required to move wedge A to the right.the pring i compreed a ditance of 175 mm. Neglect the weight of A and B. The coefficient of tatic friction for all contacting urface i =0.35. Neglect friction at the roller.
(P = 2.39 kn) 13- The mooth beam i being hoited uing a rope which i wrapped around the beam and pae through a ring at A a hown. If the end of the rope i ubjected to a tenion T and the coefficient of tatic friction between the rope and ring i = 0.3, determine the angle of ө for equilibrium. (99.2 0 )
14- Determine the mallet force P required to lift the 40-kg crate. The coefficient of tatic friction between the cable and each peg =0.1. (736 N) 15- If a force of P=200 N i applied to the handle of the bell crank, determine the maximum torque M that can be reited o that the flywheel doe not rotate clockwie. The coefficient of tatic friction between the brake band and the rim of the wheel i =0.3 (TA = 616.67 N TC = 150.00 N)