Q. 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) mv²
B) (1/2)mv²
C) (1/2)m²v²
D) (1/2)mv³
Explanation
[Solution from source] Mass leaving per second = (mass per length) × speed = mv. KE delivered per second = ½(mv)v² = ½mv³. Taking ½mv² treats m as the mass per second instead of per unit length. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.