Chapter 8, Problem 54P

The two homogeneous bars AB and BC are connected with a pin at B and placed between rough vertical walls. If the coefficient of static friction between each bar and the wall is 0.25, determine the largest angle 6 for which the assembly will remain at rest.

The brake pads at C and D are pressed against the cylinder by the spring BF. The coefficient of static friction between each pad and the cylinder is 0.15. Find the smallest tension in the spring that would prevent the cylinder from rotating when the clockwise couple M=2200lbin. is applied. Neglect the weights of the members.

The 40-lb spool is suspended from the hanger GA and rests against a vertical wall. The center of gravity of the spool is at G and the weight of the hanger is negligible. The wire wound around the hub of the spool is extracted by pulling its end with the force P. If the coefficient of static friction between the spool and the wall is 0.25, determine the smallest P that will extract the wire.

The single-threaded screw of the floor jack has a pitch of 0.5 in. and a mean radius of 1.75 in. The angle of static friction is 8.5. (a) Determine the couple C that must be applied to the screw to start lifting a weight of 4000 lb. (b) What is the couple required to start lowering the weight?

The two uniform sheets of plywood, each of length L and weight W, are propped as shown. If the coefficient of static friction is 0.5 at all three contact surfaces, determine whether the sheets will remain at rest.

roll of paper has a uniform weight of 2kN and is suspended from the wire hanger so that it rests against the wall. If the hanger has a negligible weight and the bearing at O can be considered frictionless, determine the force P needed to start turning the roll if = 30°. The coefficient of static friction between the wall ܬܐ and the paper is µ = 0.3.

The drum has a weight of 110 lb and rests on the floor for which the coefficient of static friction is μs = 0.30. Assume the center of gravity of the drum is located at its center. Pt. A : If a = 3 ft and b = 4 ft, determine the smallest magnitude of the force P that will cause the drum to start sliding.   Pt. B: If a = 3 ft and b = 4 ft, determine the smallest magnitude of the force P that will cause the drum to start tipping. Pt. C : Based on the results in the previous two parts, the impending motion of the drum is....   Slipping or Tipping?

The two 200-N blocks are pushed apart by the 15 degrees wedge of negligible weight. The angle of static friction is 10 degrees at all contact surfaces. Determine the force P required to start the blocks moving.

4. The mine car and its contents have a total mass of 6000 kg and a centre of gravity at G. If the coefficient of static friction 10 kN between the wheels and the 0.9 m •G tracks is u = 0.4 when the wheels are locked, find the normal force acting on the front wheels at B and the rear 0.15 m 0.6 m - 1.5 m wheels at A when the brakes at both A and B are locked. Does the car move? [Ans. NA = 16.5 kN, Ng =42.3 kN, the car does not move] %3D lyp