When mass M is at the position shown, it is sliding down the inclined part of a slide at a speed of 1.87 m/s. The mass stops a distance S2 = 2.15 m along the level part of the slide. The distance S1 = 1.25 m and the angle theta = 37.1 degrees. Calculate the coefficient of kinetic friction for the mass on the surface.

E = K+U = (0.5)mv^2 + mgS1sin(theta)

m cancelled?

= 9.15

W1 = [mgcos(theta)-uk mgsin(theta)]S1

W2 = -uk mgS2

uk = [ E + mgcos(theta)S1 ]/[mgS2 + mgsin(theta)S1]

m cancelled out

so

uk = [ 9.15 + (9.81)(1.25)cos37.1 ] / [ (9.81)(2.15)+(9.81)(1.25)sin37.1 ]

= 0.664

but wrong...

where did i go wrong?