# Math Help - Calc 2: Find the work W required to pump the water out ....

1. ## Calc 2: Find the work W required to pump the water out ....

2. The cross-sections are rectangles all of which are 12 m long and have variable width.

To find the width as a function of y --the height above thr ground use similar triangles.

The distance a cross -section is pumped is 7 -y

The int limits are 0 to 4

See attachment

3. Don't forget to multiply by g times the densiy of water, which is approximateley 100 Kg/m^3. This gets you the answer in terms of kg-m^2/s^2, or Joules.

4. Thanks--- I was thinking density =1kg/L which is true but as you pointed out the units would have been off.

1kg/L tranlsates to 1000kg/m^3 not 100

5. Originally Posted by Calculus26
1kg/L tranlsates to 1000kg/m^3 not 100
Oops! Yes - thanks for catching that!

6. The following attachment reflects the changes-- thanks again