- #1
Clara Chung
- 304
- 14
Homework Statement
A uniform bar AB of length L is freely hinged at one end A and released from a horizontal position.
a) Find the initial angular momentum. Ans: 3g/2L
b)Find the angular velocity when the bar is vertical. Ans: (3g/L)^(1/2)
Homework Equations
momentum of inertial of a rod through end =(ML^2)/3
The Attempt at a Solution
I have no problem with part a, I did it like this
Let N be the moment, I be the inertia of moment, a be the angular acceleration.
N = Ia
mg(L/2) = ML^2 /3 a
a= 3g/2L
But I have problem with part b, I tried to do it with energy conservation
Kr + Kt = PE
Iw^2 /2 + mw^2(L^2)/2 = mgL/2
1/3 L w^2 + w^2L = g
I would be correct if I neglect the linear KE, but I don't think it should be neglected, is my method of doing part b wrong?