00:01
Okay, we have three forces acting on the disk with a radius of 0 .11, and an observer finds the net torque is 2 .5 newton meters out of the page.
00:14
So in other words, counterclockwise rotation.
00:20
Okay, and if you look at the forces here, so we have a force, i'm just going to call them f1, f2, and f3.
00:37
And these distances we're going to call r1, r2, and r3.
00:47
Okay, and then this angle here is 45 degrees, and these are 90.
01:00
Okay, so we're given the net torque is 2 .5 newton meters.
01:05
So what is the torque produced by the unknown force f3? well, we could just look at some of the torques.
01:18
It is going to be the net torque, right? so if you add up all the torques, you should get 2 .5, because that's the net torque.
01:30
And the convention here is counterclockwise is going to be a positive torque.
01:39
Okay, so counterclockwise is a positive torque.
01:42
So let's just add up all the torques here.
01:46
So we have the torque from f1.
01:49
So that's f1 times r1 times the sine of 90 degrees, which is 1.
01:57
So we don't need to include the sine of 90 there.
02:01
Uh, the torque due to f2 is negative, because that's going to cause it to...
02:08
Or excuse me, sorry.
02:10
The torque due to f1 is negative.
02:12
The torque due to f2 is positive...