00:01
All right, so let's say we have somebody's bicep and their forearm kind of drawn like this, and this angle is 105 degrees.
00:08
And let's say that's basically the angle their bicep makes, and we're told that the forearm has a mass of two kilograms.
00:18
And it has, we'll use m for that, and it has a length of, we'll say, 30 centimeters.
00:27
So the center of mass is halfway down, so that's 15 centimeters.
00:31
We're told the bicep muscle, actually, let me redraw this.
00:34
Attaches like five centimeters from the elbow.
00:38
And they're lifting a mass that is 28 kilograms.
00:44
So we want to know what is the force, the biceps most exert on the forearm in this case.
00:49
So the torque here, the net torque, in equilibrium is going to be zero.
00:53
But if we write it out, it's going to be the force the biceps exert times the distance that they're exerting it...