Question 179: Properties of Matter

Question

Water from a pipe is coming at a rate of
100 litres per minute. If the radius of the pipe
is 5 cm, the Reynolds number for the flow is
of the order of : (density of water = 1000 kg/m
3
,
coefficient of viscosity of water = 1mPas)

Accepted Answer

Flow rate of water (Q) = 100 lit/min
= $${{100 	imes {{10}^{ - 3}}} \over {60}} = {5 \over 3} 	imes {10^{ - 3}}{m^3}$$
$$ 	herefore $$ Velocity of flow (v)
= $${Q \over A} = {{5 	imes {{10}^{ - 3}}} \over {3 	imes \pi  	imes {{(5 	imes {{10}^{ - 2}})}^2}}}$$
$$ = {{10} \over {15\pi }} = {2 \over {3\pi }}\,m/s$$
= 0.2 m/s
$$ 	herefore $$ Reynold number (R
e
) = $${{Dvho } \over \eta }$$
$$ = {{\left( {10 	imes {{10}^{ - 2}}} ight) 	imes {2 \over {3\pi }} 	imes 1000} \over 1} = 2 	imes {10^4}$$
$$ 	herefore $$ Order of R
e
= 10
4

Answer

10
6

Answer

10
4

Answer

10
3

Answer

10
2

Properties of Matter

Water from a pipe is coming at a rate of 100 litres per minute. If the radius of the pipe is 5 cm, the Reynolds number for the flow is of the order of : (density of water = 1000 kg/m 3 , coefficient of viscosity of water = 1mPas)

Choose the correct answer: