Angular acceleration and Torque when rod reaches vertical position?

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Homework Help Overview

The discussion revolves around the concepts of angular acceleration and torque as they apply to a rod released from a horizontal position to a vertical position. The problem involves calculating these quantities at the moment the rod reaches vertical orientation.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate torque and angular acceleration at the vertical position, referencing initial calculations at the horizontal position. Participants question the moment arm of the weight force and its implications for torque.

Discussion Status

Participants have engaged in clarifying the moment arm and its effect on torque and angular acceleration at the vertical position. There is a recognition that the torque and angular acceleration may be zero at this position, but no consensus on the implications or further exploration has been reached.

Contextual Notes

Participants are discussing the implications of the rod's orientation on torque and angular acceleration, particularly focusing on the moment arm being zero when the rod is vertical. The original poster is seeking assistance in understanding the transition from horizontal to vertical dynamics.

sweetpete28
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Angular acceleration and Torque when rod reaches vertical position??

A rod (mass 1.30 kg, length .670 m) attached to a frictionless axis is released from rest in the horizontal position. What is the magnitude of the torque and angular acceleration when the rod has reached the vertical position?

I know at horizontal position (immediately after release) Torque = FR = mg(L/2)= 4.27n-m and torque = I∂ giving ∂ = 21.9 rad/s^2...but how do I solve for when it hits vertical position...? Please help!
 
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When the rod is hanging vertically, what is the moment arm of the weight force about the pivot?
 


Is it 0 b/c it is through the axis of rotation?
 


Yes, correct. So what's the torque and angular acceleration at this position?
 


Both would be 0 then, right?
 


sweetpete28 said:
Both would be 0 then, right?

Right!
 

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