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Calculating Work

by norcal
Tags: work
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Jun24-07, 10:59 PM
P: 19
1. The problem statement, all variables and given/known data

The hemispherical tank shown is full of water. Given that water weighs 62.5 lb/ft3, find the work required to pump the water out of the tank. (the water will be pumped out of a spigot at the top)

2. Relevant equations

INTEGRAL from 0 to 5 of: pi*(5-h)(25-h^2)dh

3. The attempt at a solution

INTEGRAL from 0 to 5 of: pi*(h^3-5h^2-25h+125)dh

pi*((h^4)/4 - (5h^3)/3 - 12.5h^2 + 125h)

= (3125/12)*pi ft-lb.

This answer is incorrect though...anyone know what I am doing wrong? Thanks.
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Jun25-07, 07:40 AM
Sci Advisor
HW Helper
P: 25,247
You didn't use the density of water data. How would you incorporate this?

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