1. Water is flowing at the rate of 15km/hour through a pipe of diameter 14 cm into a cuboidal pond which is 50 m long and 44 m wide. In what time the level of water in the pond rise by 21 cm?

Let the level of water in the pond rises by 21 cm in t hours.

Speed of water = 15 km/hr

Volume of water flowing out of the pipe in 1 hour

= π r2h

= 231 m3

∴ Volume of water flowing out of the pipe in t hours = 231 t m3.

Volume of water in the cuboidal pond

= 462 m3 

Volume of water flowing out of the pipe in t hours = Volume of water in the cuboidal pond

∴ 231 t = 462

Thus, the water in the pond rise by 21 cm in 2 hours.

  • 50

For the pipe...

Speed = 15 km/hr = 1500000 cm/hr = 1500000/60 cm/min = 2500 cm/ min

radius = 7cm

Volume of water that flows through the pipe per minute...

=> pi * r2 * h = 49 * 2500 * pi = 122500 pi cm2

For the tank.....

volume = 4400 * 5000 * 21 cm2 = 462000000 cm2

Now, Time = distance/speed

 = 4620000 * 7/ 122500 * 22 = 1200 min = 20 hrs

I hope its right.

  • 3
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