Finding Acceleration and Reaction Forces in Rotating Thin Rod on a Hinge

AI Thread Summary
A thin rod with a mass of 0.620 kg and length of 1.08 m is subjected to a horizontal impulsive force of 14.2 N at its bottom end, prompting a discussion on calculating the acceleration of its center of mass and the hinge's reaction force. The equations of motion for rotation are applied, with the moment of inertia given as I=1/3 ML^2, leading to the relationship between angular and linear accelerations. The user struggles with determining the center of mass acceleration and seeks clarification on the connections between angular and linear quantities. The discussion also touches on finding the center of percussion, where the hinge exerts no horizontal force. Overall, the thread emphasizes the need for understanding the dynamics of rotating bodies under external forces.
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Homework Statement


A thin rod of mass 0.620 kg and length 1.08 m is at rest, hanging vertically from a strong, fixed hinge at its top end. Suddenly, a horizontal impulsive force (14.2 i ) N is applied to it.
(a) Suppose the force acts at the bottom end of the rod. Find the acceleration of its center of mass.
(b) Find the horizontal force the hinge exerts.
(c) Suppose the force acts at the midpoint of the rod. Find the acceleration of this point.
(d) Find the horizontal hinge reaction force.
e) Where can the impulse be applied so that the hinge will exert no horizontal force? This point is called the center of percussion.

Homework Equations


\Sigma\tau = FL =I\alpha \\ I=1/3 ML^2 \\ \alpha=a_{T}/L

The Attempt at a Solution


FL=1/3 ML^2\alpha
Rearranging for alpha gives
\alpha=3F/ML

I'm stuck on part a. I can work out the tangential acceleration but it's looking for the acceleration at the com. I can't recall any equations about the relationship between tangential and center of mass acceleration and can't seem to find anything on google either. Thank you in advance!
 
Physics news on Phys.org
Do you know how
angle is related to position ?
angular speed is related to velocity ?
angular acceleration is related to acceleration ?

Perhaps you can find yourself a hint by looking at the dimensions ?

google (angular speed linear speed)
 
Oops, thanks. Since α=atangentialL, α=acomL/2 right? That gives acom = 3F/2M
 
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