"Two blocks are attached to a string that passes over a frictionless pulley. One of the blocks is 4kg and rests on a rough horizontal surface. The other block is a 2kg block that hangs over the edge of the surface. When the system is released, the 2 kg mass falls from rest and attains the speed of 2m/s after traveling a distance of 3 meters"(adsbygoogle = window.adsbygoogle || []).push({});

The first question is "what is the loss in mechanical energy" and I get 56J, which is right according to my teacher. However, the second question is "what is the coefficient of kinetic friction between the 4 kg block and the rough surface?"

What I do is:

Loss in mechanical energy = energy of friction

Thus:

56 = Fd =

56 = umgd =

56 = u * 4 * 9.8 * 3m

and I get .47. However, the answer is .40. What am I doing wrong?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Friction and Pulley Problem

**Physics Forums | Science Articles, Homework Help, Discussion**