What are the Rotational Dynamics of a Thin Rod Held by a Pivot Point and String?

AI Thread Summary
The discussion focuses on the rotational dynamics of a thin rod fixed at one end and held by a string at three-quarters of its length. Key points include the calculation of the pivot point's force on the rod, the angular acceleration after the string is cut, and the transverse accelerations of both the rod's center of mass and its far end. Participants emphasize the importance of understanding torque, noting that the total downward torque must equal the upward torque, leading to confusion about the pivot's role in exerting torque. The thread highlights the need for clarity in applying rotational dynamics principles to solve the problem effectively. Understanding these concepts is crucial for accurately analyzing the system's behavior post-string cut.
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rotational dynamics rod--please help!

Homework Statement


A thin rod of length l and mass m is fixed at a far ends by a free pivot and held from rotating with a string attached at 3/4l and fixed toa ceiling. The moment of inertia of a thin rod about a far end is ml2/3

a) what is the pivot point exerting on the rod

The rope is cut at t =0 seconds. at t =0 seconds find:
b) the angular acceleration of the rod.
c) the transverse acceleration of the rod's center of mass.
d) the transverse aceleration of point A (the far end of the rod)
e) the force exerted by the pivot point

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You have to at least try the problem and explain your thoughts before asking for help.
 


First, total downward torque = upward torque.
.5mgl + Torque of pivot point = .75mgl
torque of pivot point = .25mgl.
This doesn't make sense because the pivot point can't exert a torque.
Thats all I got to...and I couldn't figure out anthing else lol
I have all the answers, I just need to understand hwo to do it.
 
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
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