Q108 / 200 · NEET 2009 (Screening) · Physics

An engine pumps water continuously through a hose. Water leaves the hose with a velocity $y$ and $m$ is the mass per unit length of the water jet. What is the rate at which kinetic energy is imparted to water ?

  • Correct answer
    A
    $\frac{1}{2} \mathrm{mv}^3$
  • B
    $\mathrm{mv}^3$
  • C
    $\frac{1}{2} \mathrm{mv}^2$
  • D
    $\frac{1}{2} m^2 v^2$

Solution

Velocity of water is \(v\), mass flowing per unit length is \(m\). Mass flowing per second \(=\mathrm{mv}\) \(\therefore\) Rate of kinetic energy or K.E. per second \(=1 / 2(m v) v^2=1 / 2 m v^3\)

Hence, the correct answer is option: 'A'.

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