Three blocks and two pulleys

1. Apr 10, 2009

Squeezebox

1. The problem statement, all variables and given/known data
The coefficient of kinetic friction between the two blocks is 0.30. The surface of the table and pulleys are frictionless.

m1=2 kg
m2=3 kg
m3=10 kg

2. Relevant equations
$$\Sigma$$F=ma
T2-m3g=m3a
T1-T2=m2a
friction-T1=m1a

3. The attempt at a solution
T2=m3g+m3a
T1=friction-m1a

friction-m1a-m3g-m3a=m2a

(friction-m3g)/(m1+m2+m3)=a
a=-6.15m/s2

The answer in my book say it is -5.7m/s2, though.

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2. Apr 10, 2009

method_man

T2=m3g-m3a
T1=m1a+m1
T2=T1+m1gμ+m2a
a=(m3g-m1gμ-m1gμ)/(m1+m2+m3)=5.7552