A block of mass 0.5 kg is pushed against a horizontal spring until the spring is compressed a distance x = 0.4 m. The spring constant is 450 N/m. When it is released the block travels along a horizontal frictionless surface then reaches a vertical circular track of radius R = 2.9 m and continues to move up the track. The block experiences friction while sliding up the track. The block reaches the top of the track with a speed of 4.1 m/s. Find the change in mechanical energy caused by friction (in J).