00:01
So we're told that this electric motor has a mass of 25kg, or the rotor.
00:12
It has a, it is said that it's going to take 4 .2 minutes for it to coast.
00:21
No, that's not right.
00:22
Yeah, 4 .2 minutes to coast to rest.
00:26
So we have a change in t of 4 .2 minutes, which if we multiply it by 60, we get 252 seconds.
00:52
We also have an angular velocity of 36, an initial angular velocity of 3 ,600 rpm.
01:05
This is the same thing as if we divide by 60 and multiply by 2 pi radians, we get 377 you have 377 radiance per second.
01:53
So we are being, and we also have a couple that is producing a torque of 1 .2 newton meters.
02:01
So we're being asked, what is the k value? what is the centroidal radius of gyration? so to do this, we're going to note that torque is equal to, we're going to use impulse momentum theorem here.
02:22
So the torque times the change in time is going to be equal to the change in l.
02:29
So the torque is equal to k squared m.
02:37
No, wait, we have a value for torque...