Question

A 7 kg block is pushed by an external force against a spring with spring constant 124 N/m until the spring is compressed by 2.1 m from its uncompressed length (x = 0). The block rests on a horizontal plane that has a coefficient of kinetic friction of 0.7 but is NOT attached to the spring.
After all the external forces are removed (so the compressed spring releases the mass) how far D along the plane will the block move before coming to a stop? The acceleration due to gravity is 9.8 m/s2 .
Answer in units of m

Answer 1

PE=W(fr)

kx²/2=μmgd

d= kx²/2μmg=
=124•2.1²/2•0.7•7•9.8 =5.7 m

Answer 2

Sorry but that was wrong