00:01
So a 71 kilogram person sits on a 39 kilogram chair, 3 .9 kilogram chair.
00:11
So let's just quickly consider that we've got a mass here.
00:16
Mass of 71 plus 3 .9.
00:23
And the chair makes contact with the floor, with a set of legs, each one being 1 .1 centimeter in diameter.
00:33
So if we've got leg diameter is 1 .1 centimeters, then our radius is 0 .55 centimeters.
00:53
So how much pressure is exerted by the chair when a person sits on it, how much pressure is exerted onto the floor? let's just think about that for a second.
01:05
So pressure is equal to force divided by area.
01:11
And the force is just the weight combination of the person.
01:14
And the chair.
01:16
So we're going to go for 74 .9 times the gravitational constant gene, 9 .8, 9 .81, 10, if you're feeling very rough about it, but we'll go for 9 .81.
01:30
And the area of the legs, well, let's just remember that we need to do this in standard units.
01:36
We need to use meters.
01:38
So 1 .1 centimeter as a diameter, 0 .55 centimeters as a radius, remembering that that will be 0 .0 .055 meters.
01:55
And so the area is of course pi times the radius squared, 0 .0 .055...