A 21 kg block on a horizontal surface is attached to a horizontal spring of spring constant k = 2.3 kN/m. The block is pulled to the right so that the spring is stretched 9.4 cm beyond its relaxed length, and the block is then released from rest. The frictional force between the sliding block and the surface has a magnitude of 46 N. \
(a) What is the kinetic energy of the block when it has moved 2.0 cm from its point of release?