A block of mass m rests on a rough horizontal surface and is attached to a spring of stiffness k. The coefficients of both static and kinetic friction are u. The block is displaced a distance xo to the right of the unstretched position for the spring and released from rest. If the value for xo is large enough, the spring force will overcome the maximum available static friction force and the block will slide toward the unstretched position of the spring with an acceleration a = ug - k/m x, where x represents the amount of stretch (or compression) in the spring at any given location in the motion. Use the values m = 10 kg, k = 210 N/m, = 0.34, and xo = 370 mm and determine the final spring stretch (or compression) xf when the block comes to a complete stop. The distance xf will be positive if to the right (spring stretched) and negative if to the left (spring compressed).

A spring with a spring constant of k = 192 N/m is initially compressed by a block a distance d = 0.23 m. The block is on a horizontal surface with coefficient of kinetic friction μk, static friction μs, and has a mass of m = 7 kg. How large would the coefficient of static friction μs need to be to keep the block from moving? Recall that to keep the block from moving, the acceleration is zero.  Assuming the block has just begun to move and the coefficient of kinetic friction is μk = 0.2, what is the block's acceleration in meters per square second?

A block of mass m = 2.00 kg situated on a rough incline at an angle of 8 = 37.0° is connected to a spring of negligible mass having a spring constant of 100 N/m (see the figure below). The pulley is frictionelss. The block is released from rest when the spring is unstretched. The block moves 10.0 cm down the incline before coming to rest. Find the coefficient of kinetic friction between block and incline. k = 100 N/m www 8 m

Khufra works at a spring factory and he was assigned to test a certain spring, whose constant is 50 N/m, attached to a 50-kg block in an incline (θ=30°). With the spring initially at equilibrium position, the block was pulled 0.3 meters down the incline by a 50-N external force applied parallel to the path. If the coefficient of kinetic friction is 0.3, determine the: a) normal force (in Newtons) b) work done by the spring (in Joules)   424.35, 2.25       -2.25, 424.35,       424.35, -2.25       2.25, 424.35