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# Power, Energy, Time Watch

1. It's been so long since I've done this type of physics work, I can't remember how to do it exactly.. Pretty sure it was A-level so I put sixth form label

A 1kW Pump can pump 30 litres/min to a height of 30 metres.
How much energy (kWh) is used to pump 1m3 of water to this height?

NB:
1000 litres = 1m3
1 litre = 1kg

Is this enough info.? It's not an actual question it's something I'm trying to work out for a report and have found these values on a manufacturer's website.

My calculation (is it really as simple as this?):
"The kilowatt-hour (symbolized kWh) is a unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour (1 h) of time."

Time taken for pump to move 1m3:
1000 / 30 = 33.3 mins/m3
Therefore, 33.3/60 = 0.555 kWh/m3, since its a 1kW pump.

Just unsure as this isn't supported other literature (typically given as 1-3 kWh/m3).
2. Well moving a quantity of water to a greater height involves doing work against gravity. If you know how long it takes to pump that quantity of water you can put a lower limit on the amount of power input to the pump. In the real world, pumps have different efficiencies depending on the design and other parameters and you'd have to consult the manufacturers tables to spec a job.

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Updated: April 12, 2013
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