Question 108298: Your help would be greatly appreciated.
The question asks me to. find the percentage efficiency. It then goes on to say.
A water pump requires an input of 0.5hp and delivers 10,000 pounds of water per hour to a house 72 feet above the pump. Given that 1 hp = 550 ft lbs/s find the pumps efficinecy?
I have an answer of 72.8% but have no idea on the steps as to how to get there. Please help. Thank you. Cheers D.
Found 2 solutions by stanbon, bucky:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! find the percentage efficiency. It then goes on to say.
A water pump requires an input of 0.5hp and delivers 10,000 pounds of water per hour to a house 72 feet above the pump. Given that 1 hp = 550 ft lbs/s find the pumps efficinecy?
I have an answer of 72.8%
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The pump should deliver (1/2)550 ft lbs/sec = 275 ft lbs/sec
There are 3600 seconds in an hour
So the pump should deliver 3600sec*275 ft lbs/sec = 990,000 ft lbs
in an hour.
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The pump is actually deliverins 10,000 lbs *72 ft = 720,000 ft lbs in an hour
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It's efficiency = 720000/990000 = 0.727272... = 72.72%
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Cheers,
Stan H.
Answer by bucky(2189) (Show Source):
You can put this solution on YOUR website! The input time rate of work is 0.5 hp and since 1.0 hp is 550 ft lbs/s, the input work rate is
half of 550 ft lbs/sec or 275 ft lbs/sec.
.
The output work is 10,000 lbs of water that is lifted 72 ft in an hour. This means that in an
hour 720,000 ft lbs of work is done. Since an hour consists of 3600 seconds, the amount of
work done per second is 720,000 ft lbs divided by 3600 seconds. The division results in
an answer of 200 ft lbs/sec.
.
So the efficiency of the pump is that it requires an input of 275 ft lbs/sec to get an output
of 200 ft lbs/sec.
.
So the efficiency is 200 divided by 275 = 0.727272 and in percent this translates to
72.7272% efficient.
.
Hope this helps you to understand the problem and to see one way of solving it.
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