# Another stumpy question

1. Nov 3, 2006

### majin

I am stuck on questions like this can anyone help
How long would it take to fill a cylindrical grow-out tank (2m high, 8m diameter, 10% freeboard) from an inlet pump delivering 25 litres of water every minute through a 25mm pipe that has 4 spray outlets?

first of all I know that the 4 spray outlets are irrelevant to the quetion and are a decoy. as well as this i know that the pipe is cylindrical

tank volume with freeBoard =90.47786842
25 L/min converts into 0.025 m3/min
to get that into m3 per sec(delivery rate) I times it by 60=1.5m3/sec

So to get the answer do I divide the delivery rate(1.5) into the tank volume i.e(90/1.5) OR do I use the delivery rate as a height(h) variable and work out volume of pipe i.e(pi*h*r*r)and then divide the volume of the pipe into the tank volume i.e(vt/vp) to get the amount in secs? any help will be greatly appreciated

2. Nov 4, 2006

### verty

That's one odd pump, delivering 0.025 m3/min but 1.5m3/sec.

You can't use the delivery rate as a height variable because height is measured in metres and delivery rate is m3/s or similar. It's always good to look at the units: volume is m3, delivery rate is m3/s.