A 20.0 kg block on a horizontal surface is attached to a lig…

A 20.0 kg blоck оn а hоrizontаl surfаce is attached to a light spring (spring constant k=8.00×103 Nm). The block is pulled 10.0 cm to the right from its equilibrium position and released from rest. When the block has moved 2.00 cm toward its equilibrium position, its kinetic energy is 12.5 J. How much work is done by the frictional force on the block as it moves ?