Pulling mass with motor through pulley (with mass)

AI Thread Summary
The discussion focuses on solving a physics problem involving torque and forces in a pulley system with mass. The user initially struggled with manipulating the torque equations but later arrived at a solution. They provided specific values for mass, force, and moment of inertia, indicating the calculations involved in determining acceleration. The importance of using two free-body diagrams to analyze the forces acting on the system was emphasized. Ultimately, the correct approach led to an acceleration value of approximately 0.44157 m/s².
Esoremada
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Homework Statement



http://puu.sh/4PDPV.png

Homework Equations



τ = I*α
τ = r*F

The Attempt at a Solution



EDIT2: Nevermind, manipulated the torque equations wrong, got it now

EDIT: Tried again and ended up with an actual answer, but still got it wrong :/
This is the FBD I used http://puu.sh/4PH7l.png

m = 1060 kg
Ft2 = 10900
I = 75.5 kg*m^2
r = 0.757 m1060a = Ft1 - 1060*9.81

τ = I*r*a
τ = r*F
F = 10900 - Ft1

I*r*a = r*F
I*a = F

75.5*a = 10900 - Ft1

1060a = Ft1 - 1060*9.81
Ft1 = 1060a + 1060*9.81

75.5a = 10900 - Ft1
75.5a = 10900 - (1060a + 1060*9.81)
75.5a = 10900 - 1060a - 1060*9.81
1060a + 75.5a = 10900 - 1060*9.81
a = (10900 - 1060*9.81) / (1060 + 75.5)
= 0.44157
 
Last edited by a moderator:
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You need two free-body diagrams.
You are given the forces on the pulley and the mass
- just sketch out the fdb's and look at what forces are present.
 

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