Help with question on forces with motion, tension, friction

AI Thread Summary
The discussion centers on a homework problem involving forces, tension, and friction, where the user struggles to formulate an accurate solution. Key points include the need for the coefficient of friction, which is not provided in the problem statement, leading to assumptions about friction's presence. The response highlights inaccuracies in the user's equations, emphasizing that tension must account for the combined weight of both the box and sled, factoring in the incline's angle. Additionally, it notes that without the coefficient of friction, the behavior of the system under tension remains unclear. The conversation underscores the importance of precise parameters in solving physics problems effectively.
shadowofanub
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Homework Statement


http://img253.imageshack.us/my.php?image=workshownph1.jpg


Homework Equations



The equations and the problem, along with the attempt at a solution are shown in the picture above

The Attempt at a Solution



The attempt is in the picture as well. Thanks guys for looking at it and helping out in advance. I have no idea with these sorts of problems where to start or what I am doing wrong.
 
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shadowofanub said:

Homework Statement


http://img253.imageshack.us/my.php?image=workshownph1.jpg

Homework Equations



The equations and the problem, along with the attempt at a solution are shown in the picture above

The Attempt at a Solution



The attempt is in the picture as well. Thanks guys for looking at it and helping out in advance. I have no idea with these sorts of problems where to start or what I am doing wrong.

Welcome to PF.
What are you given for the coefficient of friction?
 
LowlyPion said:
Welcome to PF.
What are you given for the coefficient of friction?

Thanks, its good to be here. Unfortunately all i am given is what is shown in the picture. I just assumed there was friction since it didn't say there wasn't... that's why its in my equations.
 
shadowofanub said:
Thanks, its good to be here. Unfortunately all i am given is what is shown in the picture. I just assumed there was friction since it didn't say there wasn't... that's why its in my equations.

Your equations are inaccurate. The tension must allow for the weight of both box and sled as the sinθ from the incline.

There should be a μ*m*g*cosθ between the box and the sled. When acceleration of the combined system exceeds that then it will slip. But not knowing that μ ... if it was frictionless on the sled it would slide with any tension on the rope.
 
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