# Modified atwood machine

1. Sep 29, 2008

### agnosticus

1. The problem statement, all variables and given/known data

Given in this problem is a modified Atwood Machine (block A sits on a horizontal surface with a massless rope attached which goes horizontally over a frictionless pully attached to the edge of the "cliff" which is attached downward to block B)

W of A = 45.0 N, W of B = 25.0 N, mu = 5/9

A 45 N cat falls asleep on box A. If box B is now set in motion, what is it's acceleration (magnitude and direction)?

2. Relevant equations

f$$_{kA}$$ = ($$\mu$$)n

3. The attempt at a solution

50N = (5/9)(90N). I then have found the net force on block B and found it to be -9.80 m/s$$^{2}$$. The correct answer for this is 2.13 m/s$$^{2}$$ upward. What am I missing?