= 5. The double pulley shown is attached to a 10-mm-radius shaft that fits loosely in a fixed bearing. Knowing that the coefficient of static friction kinetic friction between the shaft and the poorly lubricated bearing are g = 0.35 and k 0.40 respectively, determine the magnitude of the force P (a) to just start raising the block (20 kg) and (b) to lower the block (20 kg) at a constant rate. Note: Neglect the weight of the pulleys. K 20 kg O 45 mm 90 mm

= 5. The double pulley shown is attached to a 10-mm-radius shaft that fits loosely in a fixed bearing. Knowing that the coefficient of static friction kinetic friction between the shaft and the poorly lubricated bearing are g = 0.35 and k 0.40 respectively, determine the magnitude of the force P (a) to just start raising the block (20 kg) and (b) to lower the block (20 kg) at a constant rate. Note: Neglect the weight of the pulleys. K 20 kg O 45 mm 90 mm

International Edition---engineering Mechanics: Statics, 4th Edition

4th Edition

ISBN:9781305501607

Author:Andrew Pytel And Jaan Kiusalaas

Publisher:Andrew Pytel And Jaan Kiusalaas

Chapter7: Dry Friction

Section: Chapter Questions

Problem 7.3P: Two identical chairs, each weighing 14 lb, are stacked as shown. The center of gravity of each chair...

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Similar questions

Two identical chairs, each weighing 14 lb, are stacked as shown. The center of gravity of each chair is denoted by G. The coefficient of static friction is 0.2 at B (the contact point between the chairs) and 0.35 at A, C, and D. Determine the smallest force P that would cause sliding.
A 16-lb spool is at rest on an inclined surface. Around its center a cable is wound which travels with the same inclination of the ramp, passes through a frictionless pulley, and is attached to a block B at its other end.The coefficient of static friction between block B and the floor is 0.25. For the position shown, with the given value of α, determine: R (in) = 11,1 in r (in) = 7 in α (°) = 16° 1. The minimum coefficient of static friction that must exist between the reel and the floor of the ramp, so that the reel does NOT slide on the ramp (does not slip). 2.The minimum weight that block B must have for the reel to NOT roll down the ramp dragging block B. Do not allow for the possibility of the block turning or tipping over.
Question: An 18-kg mass is hung from a lever which rests againsta 10 degree wedge at A and is supported by a frictionless pin at C.Knowing that the coefficient of static friction is 0.25 at bothsurfacees of the wedge and that for the position shown the springis stretched 100 mm, determine (a) the magnitude of the force P forwhich motion of An 18-kg mass is hung from a lever which rests againsta 10 degree wedge at A and is supported by a frictionless pin at C.Knowing that the coefficient of static friction is 0.25 at bothsurfacees of the wedge and that for the position shown the springis stretched 100 mm, determine (a) the magnitude of the force P forwhich motion of the wedge is impending, (b) the components of thecorresponding reaction at C.
Block A supports a pipe column and rests as shown on wedge B . Knowing that the coefficient of static friction at all surfaces of contact is 0.25 and that 0 = 45°, determine the smallest force P required to raise block A.
A recording tape passes over the 20-mm-radius drive drum B and under the idler drum C . Knowing that the coefficients of friction between the tape and the drums are μs= 0.40 and μk= 0.30 and that drum C is free to rotate, determine the smallest allowable value of P if slipping of the tape on drum B is not to occur.
The block and tackle shown are used to raise a 150-lb load. Each of the 3-in.-diameter pulleys rotates on a 0.5-in.-diameter axle. Knowing that the coefficient of static friction is 0.20, determine the tension in each portion of the rope as the load is slowly raised.
The speed of the brake drum shown is controlled by a belt attached to the control bar AD . Knowing that the coefficient of static friction is 0.30 and that the brake drum is rotating counterclockwise, determine the minimum value of a for which the brake is not self-locking.
A lever AB of negligible weight is loosely fitted onto a 2.5-in.-diameter fixed shaft. Knowing that the coefficient of static friction between the fixed shaft and the lever is 0.15, determine the force P required to start the lever rotating counterclockwise.
A lever AB of negligible weight is loosely fitted onto a 2.5-in.-diameter fixed shaft. Knowing that the coefficient of static friction between the fixed shaft and the lever is 0.15, determine the force P required to start the lever rotating clockwise.
Solve Prob. 8.124 assuming that the idler drum C is frozen and cannot rotate.(Reference to Problem 8.124):A recording tape passes over the 20-mm-radius drive drum B and under the idler drum C . Knowing that the coefficients of friction between the tape and the drums are μs= 0.40 and μk= 0.30 and that drum C is free to rotate, determine the smallest allowable value of P if slipping of the tape on drum B is not to occur.
Solve Prob. 8.93 assuming that the normal force per unit area between the disk and the floor varies linearly from a maximum at the center to zero at the circumference of the disk.(Reference to Problem 8.93):A 50-lb electric floor polisher is operated on a surface for which the coefficient of kinetic friction is 0.25. Assuming that the normal force per unit area between the disk and the floor is uniformly distributed, determine the magnitude Q of the horizontal forces required to prevent motion of the machine.
The block and tackle shown are used to lower a 150-lb load. Each of the 3-in.-diameter pulleys rotates on a 0.5-in.-diameter axle. Knowing that the coefficient of static friction is 0.20, determine the tension in each portion of the rope as the load is slowly lowered.