A rectangular water reservoir is `10.8` m by `3. 75 m` at the base. Water flows into it at the rate of `18 mp e r` second through a pipe having the cross section `7. 5 cm xx 4. 5 c mdot` Find the height to which the water will rise in the reservoir in `30`minute.

Explanation

Answer
Volume of rectangular reservoir `= 1.8 xx 3.75 xx h m^3.........(1)`
`=40.5 h m^3`
Cross section of pipe `=7.5 xx 4.5 = 33.75 cm^2= 0.003375 m^2`
Distance covered in `30` minutes (`1800sec`)`= 18 xx 1800 = 32400m`
Volume of water flowed in 30minutes = Cross section of pipe xx distance covered.
`= 0.003375 xx 32400 = 109.35 m^3 ........(2)`
From `(1)` and `(2)`
`40.5 h = 109.45`
`=> h =109.35/40.5 =2.5m`
Hence the required answer is obtained.