Why Is the Normal Force on the Pulley Not Parallel to Gravity?

AI Thread Summary
The discussion centers on understanding why the normal force acting on a pulley is not parallel to the force of gravity. The confusion arises from the interaction between the pulley and the cylinder, where the tension in the string affects the direction of the normal force. It is clarified that the horizontal component of the tension causes the pulley to experience a force that is perpendicular to gravity. This results in the normal force needing to counteract the horizontal tension, leading to its non-parallel orientation. Overall, the relationship between forces and accelerations in this system is complex but essential for accurate free-body diagrams and equations.
zippeh
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Homework Statement


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Let’s have one box, one pulley, and one rolling cylinder. Each of them have mass M, the pulley’s radius is R, and the cylinder’s radius is 2R. Consider the cylinder to be rotating about its center of mass. (a) Draw correct and complete free-body diagrams. (b) Give the equation(s) that come from the free-body diagrams (there are at least 7 equations). (c) Also give the equations that relate the various accelerations to each other (there are at least 4 linear and angular accelerations to consider). You do not need to solve for anything.

Homework Equations


Στ=Iα
τ=RFsin(θ)
ΣF=ma

The Attempt at a Solution


l5pulley.jpg

[/B]
I am just confused on the portion of the normal force of the pulley. I included the above photo to demonstrate what I mean. I guess I don't completely understand why the normal force is not parallel to the gravity. It makes sense that it isn't because the T from the cylinder would be equal to 0 (T=Ma -> T=O). I am just confused. Then I guess I am confused on how to compare the accelerations together. Thanks!
 
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zippeh said:
I don't completely understand why the normal force is not parallel to the gravity
For exactly the reason you give. Since the horizontal section of string is tending to push the pulley left, the pulley mounting must resist this by exerting a force to the right.
 
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