Good grief - English units!
You need to find the volume of the tank when half full
V = (1/2) (4/3) pi r^3
then the weight of oil in the tank
W = 60 (V)
Now how far below the ground surface is the center of gravity of the oil?
You can look here http://www.youtube.com/watch?v=KBGsorVYqfo and find that the center of mass of the oil is (3R/8) below the center of the sphere
So
Distance from ground to CG of oil = 6 +10 + (3*10/8) feet
Work done = weight of oil * distance from ground to CG of oil (in foot pounds)
A spherical oil tank with a radius of 10 feet is half full of oil that weighs 60 pounds per cubic foot. Its top is 6 feet underground. How much work is needed to pump the oil out of the tank through a hole in its top?
How do I solve this? Does the fact that it its top is 6 feet underground change the work needed than if it wasn't underground?
2 answers
I assume that you have to pump the oil up to the ground by the way.
1 answer