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Nx2
Apr12-05, 03:14 PM
Hi guys, I was doing some homework when I got stuck on this question I came upon. It goes as follows...

Water is being pumped up to a water tower, which is 92.0m high. The flow rate up to the top the tower is 75L/s and each litre of water has a mass of 1.00kg. what power is required to keep up this flow rate to the tower?

Ok, so I know the formula for power is P = W/t, so I changed W into F•d and now my equation is P = (F•d)/t. then I changed F into mg and got the equation P = (mg•d)/t.
Ok, now im not sure if what im doing is right but I don’t know where to go from here… they gave me velocity but I don’t know what to do with it. Like I subbed all my values in like the mass, gravity and distance but I don’t know what to do with the “75L/s and each litre is 1.00kg.”…. any help would be appreciated, thanks.

- Tu

Gokul43201
Apr12-05, 03:17 PM
You have :
P = \frac {mgh}{t} = gh \cdot \frac {m}{t}

Does that help ?

Nx2
Apr12-05, 03:22 PM
ok... so... hmmm lol sorry i dont understand where that equation was derived from.... h is height right?

Gokul43201
Apr12-05, 03:27 PM
Yes, h is the height. I just wrote what you had written and re-arranged the terms to bring out the factor (m/t). m/t is mass per unit time. Do you not know the value of this ?

Nx2
Apr12-05, 04:24 PM
sorry... yea... we never learned that b4.

Gokul43201
Apr12-05, 04:26 PM
sorry... yea... we never learned that b4.I'm not sure what you mean by this. Do you now understand how to solve the problem, or don't you ?

Nx2
Apr12-05, 04:28 PM
ooo... ok i tried it and i got the answer!... thnx alot i appreciate it. good help.

- Tu

Nx2
Apr12-05, 04:28 PM
yea i understand... thnx