Question

water flows into a tankfrom a tap whose inner radius is 0.75cm. If the water flows at the rateof 7m/s, how many litres of water flow into the tank in half hour?​

Answer 1

Answer:

ANS: GIVEN : The inner radius of tap 0.75 cm

 The water flows at the rate of 7 m per second

Requirement : Vol of water in Litres delivered by the pipe in an hour

Area of cross section =(22*0.75 *0.75 )/7

Vol of water delivered per second = (22*0.75 *0.75*700 )/7 = 1237.5 cm3   [since 7m = 700cm]

1 hour = 60* 60 = 3600 seconds

therefore , water delivered by the pipe in a hour= 1237.5 cm3 * 3600 = 4455000 cm3

1 litre = 103 cm3 

Therefore, the quantity of water in litres = 4455000 cm3/103 cm3 = 4455 litres

Thus, the volume in litres of water delivered by the pipe in a hour = 4455 litres.

Answer 2

Solution :—

Volume of the water flows out in 1 second from the tap

= Speed of water × area of cross-section of the tap

.

Area of cross-section of the tap

$πr² \:= \: \dfrac{22}{7}\:×\:0.75\:×\:0.75$

.

Volume of water which flows out in 1 second

$= \: \dfrac{22}{ \cancel 7} \: \times \: 0.75 \: \times \: \cancel {700} {}^{100}$

(700 cm/s = 7 m/s)

.

Volume of water which flows out in $\dfrac{ 1}{2}$ hours

= 22 × 0.75 × 0.75 × 100 × 30 × 60

$( \dfrac{1}{2} h \: = \: 30 \times 60 \: s)$

= 22,27,500 cm³

= 2227.5 L

(°.° 1000 cc = 1 L)