Question

A 45 kg boy is at the edge of a circular platform of radius 3.0 m which is rotating freely at 0.5 rad s-1. The moment of inertia of the platform is 1800 kg m2. Determine the new angular velocity of the platform if the boy walks 1.0 m towards the centre of the platform.

Answer 1

Answer:

Explanation:

Conservation of angular momentum

                        L₀ω₀ = L₁ω₁

            (L+ mR₀²)ω₀ = (L+ mR₁²)ω₁

(1800 + 45(3.0)²)0.5 = (1800 + 45(3.0 - 1.0)²)ω₁

               (2205)0.5 = (1980)ω₁

                            ω₁ = 0.5568181818...

                            ω₁ = 0.56 rad/s