A 5000 kg rocket fires vertically. Exhaust speed relative to rocket is 800 m/s. For initial upward acceleration 20 m/s², find required fuel ejection rate (kg/s); take g = 10 m/s².
Physics · Mixed Chapter
JEE Main Practice

Question

A 5000 kg rocket fires vertically. Exhaust speed relative to rocket is 800 m/s. For initial upward acceleration 20 m/s², find required fuel ejection rate (kg/s); take g = 10 m/s².

G1 Physics · Accepted Answer

Step 1: Rocket thrust F = ṁvₑ. Step 2: Newton’s law at launch: F−Mg = Ma ⇒ F = M(a+g). Step 3: ṁ = M(a+g)/vₑ = 5000(20+10)/800 = 187.5 kg/s.