Two pulleys system (please check my work)

AI Thread Summary
The discussion focuses on calculating the acceleration of a two-pulley system with a massless rope and a mobile pulley weighing 20 grams. The user derives two equations based on the forces acting on the weights, leading to an acceleration of 1.43 m/s². However, there is uncertainty about the correctness of the solution, particularly regarding the tensions in the system. Other participants suggest re-evaluating the equations and emphasize the importance of using consistent units, specifically converting mass to kilograms for accurate tension calculations. The user seeks clarification and assistance in identifying any potential errors in their approach.
fishingspree2
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Homework Statement


Find the acceleration of the system
http://img266.imageshack.us/img266/4904/2pulleyszw9.jpg
The rope is massless
The mobile pulley is not massless, it weighs 20 grams.
Find the accelereation of the system

Homework Equations


F=mg
F=ma
g = 9.8

The Attempt at a Solution



for W1:
Fy = 2T-W1 = ma
2T-(500+20)*g = (500+20)*a
2T-520g = 520a (equation 1)

for W2:
Fy = W2-T=ma
300g-T=300a
T = 300(g-a) (equation 2)

equation 2 in equation 1 gives
a = 1,43


Is it correct?
 
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i don't think it's correct.. i think there is an error in the tensions, but i don't see
 
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can someone help me?
I really want to know how to do this =(
 
The equations seem to be OK. The solution is not. Try to solve again the two equations.
If you show how you solve them I can try to find the mistake, if any.
Be careful with the units. If you want to get the tension in Newtons, the mass should be in kg.
 

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