00:01
In this problem, we are given a solid defined by some planes and curves in the three -dimensional space, and we will compute its mass, and we will locate the center of mass of this object.
00:13
Okay, we have this solid e defined to be under this plane z equal to 3 plus x plus y, and above the xy plane, and on the xy plane we have these curves, y equal to root x, y equal to 0, and x equal to 1, and the density is given to be constant by this number 11.
00:42
Okay, this is a quite straightforward shape, so we can directly write down the volume element and the limits of integration.
00:53
We have x integrated from 0 to 1, y integrated from 0 to root x, and z integrated from 0 to 3 plus x plus y.
01:08
Okay, with that we write down the mass integral as rho dv, so we have 11 from 0 to 1 dx, from 0 to root x dy, from 0 to 3 plus x plus y dz.
01:27
This is different color, this is 3 plus x plus y, and all the integrals in this problem will be quite elementary, so let me just write down the simplified results for them.
01:43
Okay, the y integral is 3 root x plus x over 2 plus x to the power 3 halves, and the x integral turns out to be 53 over 20.
01:57
And now including this overall factor coming from density, we have 583 over 20, so this is the mass in appropriate units of course.
02:11
For x bar we have 1 over m integral x rho dv, so 11 over m, from 0 to 1 dx, from 0 to root x dy, from 0 to 3 plus x plus y dz, and we have this factor x.
02:30
Okay, and let me write down the results.
02:37
We have 3x plus x squared plus xy for the z integral...