GATE 2020 ME (ME2) – Question 49
The flywheel turning-moment diagram is shown for a fictitious engine. Mean turning moment is 2000 N·m and average speed is 1000 rpm. For speed fluctuations within ±2% of average, find flywheel mass moment of inertia (kg·m²).
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Correct answer: 3.55 to 3.65
Explanation
Integrate torque minus mean across the four π/2 intervals. Cumulative energy relative to start is0,−250π,+250π,−250π,0 J. Maximum fluctuation is500π J. Speed coefficient is0.04,not0.02. With ω=1000(2π/60), $I=500\pi/(0.04\omega^2)=\mathbf{3.58}$ kg·m².