A 2 kg block moving at 4 m/s on a horizontal surface compresses a spring until it stops. The kinetic friction force is 15 N and spring constant is 10000 N/m. Find the compression.

Energy balance including friction: (1/2)mv² = (1/2)kx² + 15x, so 16 = 5000x² + 15x. The positive root is about 0.0551 m = 5.5 cm. The PDF's solution omits friction but selects the same approximate option.