I am having trouble solving this problem. I know the answer is B (from http://grephysics.net/disp.php?yload=pr ... bmit=Go%21) but I don't understand the solution. Here is what I am getting.

For I_A I am getting 3mr^2.

Since r = l/sqrt{3}, I_A = ml^2. This is consistent with the answer at grephysics.net.

for I_B I am trying to get it with the parallel axis theorem (I = I_center + md^2). In this case, I_center =I_A = ml^2, and d is the distance between the two axes (A and B) which is equal to r, and as before r=l/sqrt{3}.

So= I_B = I_A + mr^2 = ml^2 + ml^2 / 3 = 4ml^2 / 3 . This is different from the answer on grephysics.net but it seems like it should be right. What am I doing wrong? Why is I_B actually equal to I_A.

Any help would be much appreciated. Thanks!

-Jax