00:01
Okay, so we have a system in equilibrium, and we have a mass hanging from the end of a uniform strut, and we have two different angles, and a, where we want to find the tension.
00:16
So the key thing here is equilibrium.
00:23
And one of the cases for equilibrium says that the net torque equals zero.
00:28
So let's look at the torques due to gravity.
00:35
These are going to produce clockwise motions.
00:42
And so the block at the very, very end equals mb, g, l, sign of theta.
00:53
And the strut at its center equals ms, g, l over 2, because it's halfway in between, that you've got to do the center of mass, sine of theta...