arthurracoon

got another hw due today, and 1 question left

any help would be appreciated


A hydroelectric dam holds back a lake of surface area A that has vertical sides below the water level. The water level in the lake is a height h above the base of the dam. When the water passes through turbines at the base of the dam, its mechanical energy is converted into electrical energy with n efficiency (0 - 1).

1. If gravitational potential energy is taken to be zero at the base of the dam, how much energy is stored in the top meter of the water in the lake? The density of water is p.

2. What volume of water must pass through the dam to produce an amount of electrical energy totalling U of electrical energy?

3. What distance does the level of water in the lake fall when this much water passes through the dam?

i need help with the first two

thanks

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arthurpostpadder

krepitch

Heh heh.

nathan

Hope this helps. I am guessing question 2 just wants you to evaluate the integral from 0 to 'x' and set it equal to U (don't forget the efficiency factor). Then the answer would be x*A.

Edit: I didn't read the question. Integrate from h to h-1

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Pariah

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arthurracoon

you integrate from h to h-1 on #2?

i had already integrated that from 0 to h for #1 - it was wrong

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arthurpostpadder

arthurracoon

got #1 by integrating from h-1 to h

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arthurpostpadder

arthurracoon

thanks

i figured it out

i had tried integrating it before, but i was integrating 0 to h for #1

got #2 by

integral 0 to h = U/n + intgeral 0 to new height x

and the answer was x*a

and then what you wrote finally clicked.

thanks

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arthurpostpadder

krepitch

No problem.

AzCards21

No problem Arthur, as a matter of fact when you finish this beginner course in theory I can show you the mathematical equations that make the "Mr. Fusion Home Energy Converter" the perfect power source for time travel.

Az

thirty-two

LMAO!

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