Question

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?

(a) mv³

(b) 1/2 mv²

(c) 1/2 m²v²

(d) 1/2 mv³

Answer 1

Correct option (d) 1/2 mv³

Explanation

 Velocity of water is v, mass flowing per unit length is m.

Mass flowing per second = mv

.'. Rate of kinetic energy or K.E. per second

= 1/2(mv)v² = 1/2mv³