An engine continuously pumps a water jet at speed v. If m is the mass of water per unit length of jet, find the rate at which kinetic energy is imparted to the water.
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An engine continuously pumps a water jet at speed v. If m is the mass of water per unit length of jet, find the rate at which kinetic energy is imparted to the water.

G1 Physics · Accepted Answer

Step 1 — Principle: Power equals the rate at which kinetic energy is imparted to the moving material. Step 2 — Working: Mass discharged per second is (mass/length)×(length/second)=mv. Step 3 — Working: Power into KE is ½(mv)v²=½mv³. Correct answer: A — ½mv³.