Work Energy and Power - Result Question 18
20. An engine pumps water continuously through a hose. Water leaves the hose with a velocity $v$ and $m$ is the mass per unit length of the water jet. What is the rate at which kinetic energy is imparted to water?
[2009]
(a) $m v^{2}$
(b) $\frac{1}{2} m v^{2}$
(c) $\frac{1}{2} m^{2} v^{2}$
(d) $\frac{1}{2} m v^{3}$
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Answer:
Correct Answer: 20. (d)
Solution:
- (d) $m=$ mass per unit length
$\therefore$ Mass flowing per second $=m v$
Rate of K.E. $=\frac{1}{2}(m v) v^{2}=\frac{1}{2} m v^{3}$
