Variable Mass Systems — JEE Main Physics MCQs with Solutions
Free JEE Main Physics Variable Mass Systems MCQs with step-by-step solutions (2 questions). Part of Centre of Mass, Momentum & Collisions. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Variable Mass Systems · easy · numerical
Water leaves a fire hose at 20 kg/s with speed 30 m/s. The reaction force on the hose is:
A. 60 N
B. 600 N ✓ Correct
C. 300 N
D. 150 N
Solution: F = v(dm/dt) = 30×20 = 600 N.
Q2 — Variable Mass Systems · medium · numerical
A rocket's thrust is 4000 N with exhaust speed 800 m/s. The fuel burn rate is:
A. 5 kg/s ✓ Correct
B. 8 kg/s
C. 2 kg/s
D. 10 kg/s
Solution: dm/dt = F/v_rel = 4000/800 = 5 kg/s.