Physics Problem Involving Moment and Acceleration

AI Thread Summary
The discussion centers on a physics problem involving a uniform board hinged at one end and released from an angle. The initial approach used conservation of energy but did not yield a solution. The correct method involves considering rotational kinetic energy and the moment of inertia, focusing on the tangential acceleration rather than velocity. Key factors include the center of rotation and the forces producing torque. Understanding these concepts is crucial for solving the problem accurately.
taylorkrauss
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A uniform board length L hinged about its lower end, held at θ above the horizontal is released from rest. As it passes through the horizontal what is the tangential acceleration of its outer tip?



At first when I attempted this, I applied conservation of energy.
(1/2)mv^2+mgh=(1/2)mv^2 + mgh
but I did not get an answer.
Then I decided could the answer just be L*gravity?? Any help given will be much apreciated! Thank you!
 
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welcome to pf!

hi taylorkrauss! welcome to pf! :smile:

your kinetic energy must include the rotational KE:

KE = 1/2 mvc.o.m2 + 1/2 Ic.o.mω2 = 1/2 Ic.o.rω2 :wink:​
 
You're looking for tangential acceleration, not velocity. So think about the moment of inertia, where the center of rotation is, and what forces are acting to produce a torque at the instant in question.
 

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