Chapter 14, Problem 30P

At the instant when a force of F = (8t2) Ib is applied on the 10 Ib block, the block was moving at 4 ft/s. Assuming the coefficient of friction between the block and the surface is Hk = 0.2, determine the velocity of the block when it moves s = 30 ft. v = 4 ft/s F = (8f) lb

The 56.28 kg crate is hoisted up the 0 = 27° incline by the pulley system and motor M. If the crate starts from rest and, by constant acceleration, attains a speed of 8.17 m/s after traveling 7.84 m along the plane, determine the supplied power to the motor if the crate has moved 8 m and the coefficient of kinetic friction between the plane and the crate is Hk = 0.3. Neglect friction along the plane. The motor has an efficiency of 0.691. M

The crate has a mass of 80 kg and is being towed by a chain which is always directed at 20° from the horizontal as shown. Determine the crate's acceleration in t = 2 s if the coefficient of static friction is µ̟ = 0.4, the coefficient of kinetic friction is Pk = 0.3, and the towing force is P = (90t) N, where t is in seconds. %3D 20

A 0.8 Mg car travels over the hill having the shape of a parabola. If the driver maintains a constant speed of 9 m/s, determine both the resultant normal force and the resultant frictional force that all the wheels of the car exert on the road at the instant it reaches A. y = 20 (1 – À00 -80 m-

1. If the 50-kg crate starts from rest and achieves a velocity of v = 4 m/s when it travels a distance of 5 m to the right, determine the magnitude of the force P acting on the crate. The coefficient of static friction between the crate and the ground is u. = 0.3 30

If the coefficient of kinetic friction between the150-lb crate and the ground is uk = 0.2, %3D determine the speed of the crate when t = 4 s. The crate starts from rest and is towed by %3D the 100-lb force. 100 lb 30°

1. The 400-kg mine car is hoisted up the incline using the cable and motor M. For a short time, the force in the cable is F = (3200f²) N, where t is in seconds. If the car has an initial velocity v₁ = 2 m/s at s = 0 and t=0, determine the distance it moves up the plane when t = 2 s. 17 15 v₁ = 2 m/s

The 20-kg crate is subjected to a force having a constant direction and a magnitude F = 100 N. When s the crate is moving to the right with a speed of 8 m/s. Determine its speed when s = 25 m. The coefficient of kinetic friction between the crate and the ground is 15 m, %3D µ= 0.25 30°

2. The block (A) has a mass of 10 kg and the coefficient of dynamic friction between the block and the ground is μ = 0.3. Block B has a mass of 15 kg and slides down a frictionless pole. If the blocks start from at x=0 calculate: a. The distance block A moves after block B has fallen 4 m b. The relationship between the speed of A and the speed of B c. The work done by friction on block A d. The velocity of block B. B 2m A