# Pulley problem (with friction)

1. Sep 1, 2009

### wicked_vixen

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

......................................__m5____
.......|\.........................../.............|
.......|..\......................./...............|
..m1.|...m2.................m4...............|.m6
.......|.....\................./..................|
.......|...45.\___m3___/30................|

- All the boxes (m1, m2, m3, m4, m5) are connected by strings.
- m2 and m4 are leaning on the wall.
- m3 and m5 are standing
- m1 and m6 are hanging
- the first incline (the one at the left) has an angle of 135 degrees (conventional) >> thus 45 degrees north of west (in a manner of speaking)
- the second incline has an angle of 30 degrees

m1=35 kg

m2=15kg
us2=0.40
uk2=0.20

m3=7.0kg
us3=0.70
uk3=0.60

m4=5.0kg
us4=1.0
uk4=0.80

m5=15kg
us5=uk5=0

m6=10kg

AT WHAT ACCELERATION WILL IT MOVE?

2. Relevant equations
g = 9.8 m/s2
sin 30 = 0.500
cos 30 = 0.866
sin 45 = cos 45 = 0
Ff = u*FN
vf = vi + at
d = vit + 1/2at2
vf2 = vi2 + 2ad
v = (vf + vi) / 2

3. The attempt at a solution
I tried to get all m*us and added them all together but it doesn't seem right. And I didn't know where to go next and I'm not sure if I even started right.

Last edited: Sep 1, 2009
2. Sep 1, 2009

### kyiydnlm

draw free-body diagrams first; then you will find the answer by yourself.