Engineering
Physics
Momentum and Energy Conservation for System of Particles
Moment of Inertia
Angular Momentum and Conservation of Angular Momentum
Question
A disc has a radius of 1m and moment of inertia of 4600 kg m2. The disc is rotating with angular velocity 1 rad/sec about fixed axis passing through its centre and perpendicular to its plane. (see figure). An 80 kg man runs with a velocity of 5 m/s, on a line tangent to the rim disc and grabs hold of a pole on the rim. The change in angular velocity of disc is _____ × 10–2 rad/sec.
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Solution
Conservation of angular momentum about the fixed axis.
4600 × 1 + 1 × 80 × 5 = (4600 + 80 × 12) × ωf
ωf = 32/468
Δω = 0.068
6.8 × 10–2 = 7 × 10–2