Chapter 8, Problem 88P

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 leather rein used to fasten the horse to the hitching rail weighs 3.5 oz per foot. The coefficient of static friction between the rail and the rein is 0.6. If a 34-lb force acting on the bridle is sufficient to restrain the horse, determine the smallest safe length L for the free end of the rein.

The 60-lb plank rests on a frictionless roller at A, and the 20-lb triangular support BD. Both bodies are homogenous. The coefficients of static friction are 0.4 at B and 0.3 at D. Determine the largest force P that can be applied to the plank without initiating motion.

When the 0.05-kg body is in the position shown, the linear spring is stretched 10 mm. Determine the force P required to break contact at C. Complete so lutions for (a) including the effects of the weight and (b) neglecting the weight.

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The rope running over two fixed cylinders carries the 4-kg mass at one end. Determine the force P that must be applied to the other end to initiate motion. The coefficient of static friction between the rope and the cylinders is 0.15. BISECTION METHOD

Q1: The tractor has a weight of 4500 lb with center of gravity at G. The driving traction is developed at the rear wheels B, while the front wheels at A are free to roll. If the Q2: The mine car and its contents have a total mass of 9 Mg and a center of gravity at G. If the coefficient of static friction between the wheels and the tracks is u, = 0.4 when the wheels are locked, find the normal force acting on the coefficient of static friction between the wheels at B and the ground is u, = 0.5, determine if it is possible to pull at P = 1350 lb without causing the wheels at B to slip or the front wheels at A to lift off the ground. front wheels at B and the rear wheels at A when the brakes at both A and B are locked. Does the car move? 10 kN 0.9 m G 0.15 m 3.5 ft 1.25 ft 0.6 m- 4 ft -1.5 m- 2.5 ft

The figure shows a bar in equilibrium position resting on the floor at point A and on the wall at point B. If the mass of the bar is m and the angle it makes with the floor is θ = π/6, find the magnitudes of the frictional and normal forces at points A and B.

A bicyclist applies a 32-N force F to the brake lever of her bicycle as shown. Determine the corresponding tension T transmitted to the brake cable. Neglect friction at the pivot O. Assume a = 23 mm, b = 82 mm.