00:01
Hi, here for the first part we need to calculate how much work done to build a pyramid.
00:08
We are given the details in the question.
00:11
So here first of all, we will note down the formula to calculate the potential energy.
00:17
So here formula for potential energy pe is equal to mass into gravitational acceleration into height.
00:24
So here further we know that formula to calculate the volume of a pyramid will be equal to base area multiplied with height divided by 3 and here we know that the value of base area is equal to side length multiplied with side length.
00:51
So here now using all this value here in our case, we have base area is equal to 765 feet multiplied with 765 feet which is equal to 585 comma 225 square feet.
01:10
Now further we know that formula to calculate the volume of pyramid.
01:16
So substituting the value here we have 585 comma 225 multiplied with height which is 481 feet divided by 3.
01:28
So calculating this we have volume equals to 94 comma 524 025 cubic feet.
01:37
So this is the volume of the pyramid.
01:39
Now here further for the next step we need to calculate the work.
01:45
Here in our case we know that work is equal to potential energy.
01:51
So here we need to calculate this.
01:54
Now here we know that this formula stands for mgh.
01:58
We don't have mass but mass can be obtained if we divide volume with if we multiply volume and density.
02:06
So here in the question we are given density to be 150 cubic pound.
02:10
So here it is 150 pounds per cubic foot.
02:17
So here using this value we can find the value of mass.
02:21
So mass m is equal to 94 comma 542 comma 025 divided by 150...