Are Your Calculations for Energy and Friction Correct?

[HaoPhysics]

Homework Statement

Homework Equations

The block has potential energy U at the top of the ramp, and this is transferred to kinetic energy K at the bottom, which is then trasnfered to work done by friction, W_fr.
U = K Conservation of energy
K = W_fr Conservation of energy
g = 10 m/s²

The Attempt at a Solution

U = mgh = 3*45*10 = 1350 J
1350 J = W_fr = F_fr * d = m*g*u*d = 3*10*1*d
1350 = 30*d
d = 45 m

This does not match the answers. Am I doing anything wrong?

 

[gneill]

Your calculations are correct. There is likely an error in the problem statement. I suspect that they intended the coefficient of kinetic friction to be 0.1. Your answer of 45 m is correct for the given information.

 

[HaoPhysics]

Your calculations are correct. There is likely an error in the problem statement. I suspect that they intended the coefficient of kinetic friction to be 0.1. Your answer of 45 m is correct for the given information.

That is a very good point. We usually don't see coefficients of friction to be 1.0, so it probably was 0.1. I just wanted to make sure my understanding of work-energy relationship was correct. Thanks!