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?
Answer & explanation
Correct answer: option 4
mass per unit length : m
Length covered by water in 1 second is v
Amount of mass passing per second = mv
Rate of K.E. = $\frac{d(mv^2)}{2dt}= \frac{dm}{2dt}v^2= \frac{mv}{2}v^2 = \frac{mv^3}{2}$