Question

One end of a cylindrical has a radius of 1.5 cm. water $(density=1.0\times {10}^{3}kg/m^2)$ stream steadily out at 7.0 m/s. the rate at which mass is leaving then pipe is

• A. 2.5 kg/s
• B. 4.9 kg/s
• C. 7.0 kg/s
• D. 48 kg/s

Answer 1

Answer: (B)

4.9 kg/s

radius $=1.5cm=15\times {10}^{-3}m$

density $\rho ={10}^{3}kg/m^3$

velocity $V=7m/s$

We know volume passing in per second is

$V=A\times v$

$A=$

cross section of the pipe

$V=\pi r^2\times \nu \times \rho v=$ velocity of stream

or $V=\frac{22}{7}\times 225\times {10}^{-6}\times 7\times {10}^3$

or $V=4.9kg/s$

correct - option-B