Chapter 8, Problem 57P

The light bar is used to support the 50-kg block in its vertical guides. If the coefficient of static friction is 0.30 at the upper end of the bar and 0.40 at the lower end of the bar, find the friction force acting at each end for x = 75 mm. Also find the maximum value of x for which the bar will not slip 50 kg A 300 mm

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 three identical rollers are stacked on a horizontal surface as shown. If the coefficient of static friction µ is the same for all pairs of contacting surfaces, find the minimum value of μs for which the rollers will not slip. - Answer: Us=

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

The square-threaded screw has a mean diameter of 20 mm and a lead of 4 mm. If the weight of the plate A is 5 lb, determine the smallest coefficient of static friction between the screw and the plate so that the plate does not travel down the screw when the plate is suspended as shown.

If the cocfficient of static friction at C is µ, = 0.3, determine the largest force F that can be applied to the 5-kg ring. without causing it to slip. Neglect the thickness of the ring

The disk clutch is used in standard transmissions of automobiles. If four springs are used to force two plates A and B together, determine the force in each spring required to transmit a moment of M = 600lb-ft across the plates. The coefficient of static friction between A and B is u, = 0.3.

Determine the greatest angle 0 so that the ladder does not slip when it supports the man (of the mass of m) in the position shown. The coefficient of static friction at A and B is Hs. Ignore the weight of the ladder. Use m = 93 kg, Hs = 0.48, a=2.5m, b=0.25m, g = 9.81 m/s?. b a e to the nearest integer (deg) =

The pickup truck pulls the wooden crate, as shown in Figure 2. The truck has a mass of 1.25 Mg and a center of mass at G. The coefficient of static friction between the truck's wheel and the ground is µ = 0.5, and between the wooden crate and the ground is µs' = 0.4. Determine the greatest weight of the wooden crate the pickup truck can pull if:   a) the truck has rear-wheel drive while the front wheels are free to roll, and   b) the truck has four-wheel drive.