 So let's do this problem here. It says, if we have a barometer that is at sea level and it's measuring 760 millimeters and the density of mercury is 13.5 grams per mill, what would be the height of a column of water at the same temperature, pressure, everything? So the thing we have to remember in order to do this is that equation I just gave you. So the height of 1 divided by the height of 2 equals the density of 2 over the density of 1. So we've got the height of 1, density of 1. We know the density of water. It's going to be 1.0 of grams per mill, like that. So we should be able to figure out, well, what is the height of water? So let's just rearrange this to say our hood. So we'll say mercury is 2 and water is 1. So that would be our equation if we're going to solve for mercury and water. And we want the height of water, so we'll rearrange this equation, density of mercury, the height of mercury divided by density of water. Is everybody okay doing that? That part? Okay, from here, we're going to plug in. 13.5 grams per mill, height 760 millimeters, divided by grams per mill, like that. Grams per mill cancels with grams per mill. Is everybody okay with doing that? So that should give us a height in millimeters of the water column. Has anybody calculated it yet? Pretty tall, if you have not sure. So 13.5 times 760 is going to give us a value of 1,0,2,6,0 millimeters. Okay, so that's pretty tall. So two, three significant figures. Well, we'll make this meter. So divide by 1,000. That gives us 10.3 meters of water. So instead of having a handheld device that's only 760 millimeters tall, relatively, you would need something that would be like 10.3 meters. Is everybody okay with thinking about that? So it's fairly impractical to use water as a barometer. Any questions on this one? How are you going to choose which is the height more than the height 2? It would be either one of them. You just have to be consistent. I just picked water there, so I wouldn't have to rearrange more. So already the water was in the numerator on the top, and that's why I picked it there. But yeah, that's a good question. It doesn't matter. You could pick either one. You just have to rearrange it to make sure you're solving for the right one. Is everybody okay with understanding that question?