Work needed to pump water to a tank

In summary, the conversation discusses a question with a diagram and answer key attached. The problem involves finding the work needed to pump water into the bottom and top halves of a sphere. The conversation also includes a Wolfram query and a discrepancy in the results compared to the answer key. The person providing the answer points out a flaw in the first integral and suggests correcting it.
  • #1
theBEAST
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0

Homework Statement


I have attached the question with a diagram and answer key.


The Attempt at a Solution


What I did was found the work needed to pump the water into the bottom half of the sphere from 90-100 and then add that to the work needed to pump the water into the top half of the sphere.

integral from 0 to 10 9800pi(100-x^2)(90+x) + integral from 0 to 10 9800pi(100-x^2)(100+x)

When I plug in my numbers using wolfram I get:
http://www.wolframalpha.com/input/?i=integrate+from+0+to+10+(9800pi(100-h^2)(190+2h))

Which is slightly off compared to what the answer key gets:
http://www.wolframalpha.com/input/?i=integrate+from+-10+to+10+(9800pi(100+x)(100-x^2)

Does anyone know why they would be different? I feel like my logic is correct...
 

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  • #2
Your flaw is in your first integral. When x=0 (in the first integral), you're 90m above the ground. Yet, the diameter is 10m, when it should be 0m ;)
 

1. How is the work needed to pump water to a tank calculated?

The work needed to pump water to a tank is calculated by multiplying the force required to move the water (in Newtons) by the distance the water needs to be lifted (in meters).

2. Does the height of the tank affect the amount of work needed?

Yes, the height of the tank does affect the amount of work needed. The higher the tank, the more work is required to pump the water to that height.

3. Is the work needed to pump water to a tank affected by the weight of the water?

Yes, the weight of the water being pumped does affect the work needed. The more water that needs to be pumped, the more work is required.

4. Does the type of pump used affect the amount of work needed?

Yes, the type of pump used can affect the amount of work needed. Different types of pumps have different levels of efficiency and can require different amounts of force to move the water.

5. How can the work needed to pump water to a tank be reduced?

The work needed to pump water to a tank can be reduced by using more efficient pumps, reducing the height of the tank, and minimizing the amount of water being pumped by using smaller tanks or finding ways to conserve water.

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