Finding the Angle Phi in a Gravity-Affected System

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Homework Help Overview

The discussion revolves around a problem involving a gravity-affected system where two bodies, one with mass m and the other with mass M, are analyzed to find the angle phi. The original poster seeks assistance in understanding the forces acting on the masses and their motion relative to each other.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the forces acting on mass m, including tension and gravitational forces. There is an exploration of how to relate the motion of mass m to mass M and the overall system's acceleration. Questions arise regarding the application of forces and the use of D'Alembert's principle.

Discussion Status

The discussion is ongoing, with some participants providing hints and suggestions for analyzing the forces involved. There is a recognition of the need to clarify the motion of the contraption and how to apply Newton's laws effectively. The original poster expresses a sense of progress after receiving feedback.

Contextual Notes

Participants are navigating the complexities of the problem, including the relationship between the two masses and the forces acting on them. There is an emphasis on understanding the setup and the implications of the forces involved, with no explicit consensus reached yet.

radagast_
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Hello.
I have the attached problem.
The body whose mass is m doesn't move relative to the body M. Them both are affected only by gravity.
I need to find the angle phi.

Can anyone please help me?

http://img135.imageshack.us/img135/4690/1113169793tx6.gif"

Thank you.
 
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Show us what you've done so far and point out where you got stuck.

Hint: What's the motion of that contraption along the incline?
 
Doc Al said:
Show us what you've done so far and point out where you got stuck.

Hint: What's the motion of that contraption along the incline?

well, I tried to draw the forces on the little mass m, and I know the whole contraption is under a force (mgsin(alpha)), and I got to the point that on the little mass, I have the tension and the mg force and a d'elambert force to the left.
Im kinda stuck on doing that on the whole thing. I don't really know how to relate to the little mass in reference with the M mass, ie - I want to write the motion equations from the accelerating contraptions' POV, but then I don't know how to take the m mass's forces (should I take it as another force, ie mg+Mg=mgsinalpha, or not...).
 
D'alembertian forces? Let's have none of that crazy talk! :wink:

What's the acceleration of the contraption (and thus mass m)? Analyze forces parallel and perpendicular to the incline and apply good old Newton.
 
Thanks.
I think I got it... I'll try it and see how it turns out
:)
 

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