Re: classical physics - rod anchored to ground, rotational inertia
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schweitzer, im taking the the 3rd too, gl.
both are wrong. im beginning to think it could be rotational...for the first...you cant take the hight of the center of mass cuz it just wants the tip of the rod and theyll be moving at different angular velocities. if the w=v/r. im thinking if you can scale that out then maybe.
the answers (3gl)^.5
and #2 was (55/2)* mr^2
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Yeah you're right I was way off.
My potential was fine but kinetic energy should change from .5*m*v^2 to its rotational equivalent: .5*I*w^2
then:
MgL/2 = .5*I*w^2 since w=v/r then
MgL/2 = .5*I*(v/L)^2 -> V = [M*g*L^3/I]^.5
I had to look up I of rod and found I=1/3*m*L^2
then you get V=[3*g*L]^.5
Not sure about the second question but I'll try and figure it out.
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