00:01
So this is chapter 9 problem 41.
00:03
A marble column of cross -sectional area 1 .4 meters squared supports a mass of 25 ,000 kilograms.
00:11
A, what is the stress within the column? b, what is the strain? so this is my column here, my marble column, and it has a cross -sectional area.
00:24
So if we just cut out a slice here.
00:27
Imagine, let's get a better.
00:30
Just take a cross -sectional slice out like that then the dotted line box it has an area of 1 .4 meter squared and then the mass of the the full marble column is going to be 25 ,000 kilograms so to find the stress and the strain we just need to look at basically the pressure that this can handle this marble column and so pressure you should know from previous studies in the chapter in chapter 9 that it's equal to the force divided by the area.
01:11
So in this case, the only force that we know of is one that's acting on the mass, which is gravity, right? so we're going to have mass times gravity divided by the area, 1 .4 meter squared, and we should get our stress.
01:27
And then to find the strain, we want to take the stress and divide it by young's modulus, which is a constant.
01:36
And we should be able to get our answer.
01:46
Well, it's a constant, but it's a mechanical property that measures the stiffness of certain materials...