Question

Water flows through 3 sections: A (large diameter) to a smaller

section B and then to section C. If the sizes of the 3 sections are: C

< B < A. and if the ratio of sections A to C are 8:3 and if the speed

of water in section A is 4m/s, then what is the speed of the water

in section C?​

Answer 1

Answer

Correct option is

A

189cm

3

/s

Let the velocity at x = v

x

and that at y = v

y

.

By the equation of continuity,

v

x

v

y

=

1.5cm

2

3cm

2

=2

By Bernoulli's equation,

P

x

+

2

1

pv

x

2

=P

y

+

2

1

pv

y

2

or,P

x

−O

y

=

2

1

p(2v

y

)

2

−

2

1

pv

y

2

=

2

3

pv

y

2

or, 600

m

2

N

=

2

3

(1000

m

3

kg

)v

x

2

or, v

x

=

0.4m

2

/s

2

=0.63m/s

The rate of flow =(3cm

2

)(0.63m/s)=189cm

3

/s.