A block of mass 1.3 kg is attached to a horizontal spring that has a force constant 1 200 N/m as shown in the figure below. The spring is compressed 2.0 cm and is then released from rest. a F x x = 0 X X b (a) A constant friction force of 3.6 N retards the block's motion from the moment it is released. Using an energy approach, find the position x of the block at which its speed is a maximum. cm (b) Explore the effect of an increased friction force of 13.5 N. At what position of the block does its maximum speed occur in this situation? cm