Chapter 8, Problem 104P

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.

The man is trying to push the homogeneous 20-kg ladder AB up a wall by applying the horizontal force P. Determine the smallest value of P that would move the ladder. The coefficient of static friction between the ladder and both contact surfaces is 0.3.

Determine the minimum force P to prevent the 30-kg rod AB from sliding. The contact surface at B is smooth, whereas the coefficient of static friction between the rod and the wall at A is = 0. - 4m -

A. Determine the minimum horizontal force P required to hold the crate from sliding down the plane. The crate has a mass of 100 kg and the coefficient of static friction between the crate and the plane is μs =0.25.B. Determine the minimum force P required to push the crate up the plane. The crate has a mass of 50 kg and the coefficient of static friction between the crate and the plane is μs =0.25.

If each box weighs 150 lb, determine the least horizontal force P that the man must exert on the top box in order to cause motion. The coefficient of static friction between the boxes is μs = 0.54, and the coefficient of static friction between the box and the floor is μ's = 0.24.

Block A has a mass of 29 kg and block B has a mass of 41 kg. The two blocks are stacked on the ramp with an incline of 0 = 32.2°. Determine the largest horizontal force F that can be applied to block B without either block moving for each of the following two cases: a.) The friction coefficient for the contact between blocks A and B is Hs1 = 0.6 and the friction coefficient for the contact between block A and the ramp is Hs2 = 0.22. b.) The friction coefficient for the contact between blocks A and B is µs1 = 0.6 and the friction coefficient for the contact between block A and the ramp is Hs2 = 0.55. F A Part a) The limiting slip condition occurs at the contact between A and the ramp v The maximum force before either block A or B slips is N Part b) The limiting slip condition occurs at the contact between A and B The maximum force before either block A or B slips is >

Q3) The three flat blocks are positioned on the 30° incline as shown, and a force P parallel to the incline is applied to the middle block. The upper block is prevented from moving by a wire which attaches it to the fixed support. The coefficient of static friction for each of the three pairs of mating surfaces is shown. Determine the maximum value which P may have before any slipping takes place. 30 kg 50 kg 40 kg H₂=0.45 H₂ = 0.30 P H4,-0.40 30° Fig.(Q).

Determine the force P required to force the 15° wedge under the 95-kg uniform crate which rests against the small stop at A. The coefficient of friction for all surfaces is 0.36.

2. Two men are sliding a 100-kg crate up an incline. If the lower man pushes horizontally with a force of 500 N and if the coefficient of kinetic friction is 0.4. determine the tension T which the upper man must exert in the rope to maintain motion of the crate. 30 100 kg 15 = 0.40