00:01
Okay, so we're doing chapter 29, problem 33.
00:05
So in this problem, we have a circuit with a resistance r, and these two wires are connected by a free -moving metal bar.
00:17
And this is all in a b field that is pointing into the page.
00:24
Okay, and it gives us the length of the rod is going to be 0 .25 meters.
00:30
The resistance of the resistor is 6 oms.
00:36
The magnitude of the b field is 1 .2 tesla.
00:42
And what we're asking here is at when the current is counterclockwise and at a magnitude of 1 .75 amps, we want to figure out how fast this bar is moving in which direction.
00:58
So what's v? okay.
01:01
So we can do this a couple of different ways, but the way i propose is doing energy conservation.
01:10
So the rate and change of work must be equal to the rate and change of thermal power given by this.
01:18
So if we rearrange this equation, we can solve for v.
01:23
We're just going to worry about the magnitudes here.
01:25
So the magnitude of v is given as a magnitude of i times r, both...