Water flows from a hose-pipe of of internal diameter 1cm at a rate of 5 litres per minute. at what speed is the water flowing through the pipe?

1 litre = 1000 cubic centimeters

In the question, 5000 ccs pass every minute. 

Think of that as a rod of of water, 1cm in diameter 

Volume = length*area = 5000 cc 

length = volume/area 

area = pi*r^2, where r = radius of pipe. 

r = 0.5 cm (half the diameter) 

length = 5000/(pi*(0.5)^2) cm 

= 20000/pi cm 

That's the length per minute, so the speed is 

(20000/pi) cm/minute<<< 

(20000/(60*pi)) cm/second<<<