Question

A light spring with force constant 3.85 N/m is compressed by 8.0 cm as it is held between a 0.25 kg block on the left and a 0.50 kg block on the right. Both blocks and the spring are resting on a horizontal surface. When the blocks are simultaneously released from rest, find the acceleration with which each block starts to move given that uk 0.1 between the blocks and the surface.

Answer 1

Spring force on each block F_5 = Kx = (3.85 N/m) (0.08m) = 0.308 N Kinetic friction on the first block is f_1 = K m_1 g = 0.1 times 0.25 times 9.8 m/s^2 = 0.245 N kinetic friction on second block is f_2 = K m_2 g = 0.1 times 0.5 times 9.8 = 0.49 N The second block does not more as the friction force is greater than the spring force The net force on the first block, F_net = Kx - k m_1 g = 0.308 - 0.245 = 0.063 N Acceleration = a a = F_net/rn = 0.063 N/0.25 kg a = 0.252 m/s^2 The first block accelerates from rest to 0.252 m/s^2 second block acceleration = 0