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## Homework Statement

A relaxed spring with spring constant k = 70 N/m is stretched a distance di = 63 cm and held there. A block of mass M = 7 kg is attached to the spring. The spring is then released from rest and contracts, dragging the block across a rough horizontal floor until it stops without passing through the relaxed position, at which point the spring is stretched by an amount df = di/7.

## Homework Equations

W = F*d

KE = 1/2 k*x^2

KE = 1/2 m*v^2

## The Attempt at a Solution

All I need is to find the

**but i havent been able to get the right value yet.**

__change in kinetic energy,__I tried to find the change in kinetic energy by using 1/2kx^2, using .63 m as x, also trying 0.63 - 0.09 m as x, but i havent gotten the right value for change in KE.

Please help.