Calculating Work Required to Empty a Tank of Beer

  • Thread starter Thread starter eumyang
  • Start date Start date
  • Tags Tags
    Beer Tank
eumyang
Homework Helper
Messages
1,347
Reaction score
11
So a cousin has asked me for Calculus help, but my Calculus is rusty. She's in Calculus II (of a 3-semester sequence in the US) and is on Work. I decided to make up a problem for her, but I want to make sure I know what I'm doing.

Homework Statement


A cylindrical tank (16 feet high with a radius of 4 feet) is half full of beer that weighs 63 pounds per cubic foot. Find the work requred to pump beer out through a spout in the top of the tank.

Homework Equations


W = {\int_a}^b F(x) dx

The Attempt at a Solution


I just would like to know if I had set up the integral right.

The volume of a disk of beer would be \pi \cdot 4^2 \Delta\ y
The weight of a disk of beer would be 63 \cdot 16\pi \Delta y = 1008\pi \Delta y
The distance to move a disk of beer to the top would be 16 - y

W = {\int_0}^8 1008\pi (16 - y) dy
Is the integral this? Seems too simple. If so, I can take it from here.

Thanks in advance.
 
Physics news on Phys.org
That looks good to me.
 
Whew! Glad I'm not totally out of it. Thanks.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top