Mechanical Properties of Fluids - Result Question 9

9. The cylindrical tube of a spray pump has radius, $R$, one end of which has $n$ fine holes, each of radius $r$. If the speed of the liquid in the tube is $V$, the speed of the ejection of the liquid through the holes is :

[2015 RS]

(a) $\frac{VR^{2}}{nr^{2}}$

(b) $\frac{VR^{2}}{n^{3} r^{2}}$

(c) $\frac{V^{2} R}{nr}$

(d) $\frac{VR^{2}}{n^{2} r^{2}}$

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Answer:

Correct Answer: 9. (a)

Solution:

  1. (a) Inflow rate of volume of the liquid $=$ Outflow rate of volume of the liquid

$\pi R^{2} V=n \pi r^{2}(v) \Rightarrow v=\frac{\pi R^{2} V}{n \pi r^{2}}=\frac{V R^{2}}{n r^{2}}$