Question

Two 25 kg children are sitting on a merry-go-round that is rotating at 0.10 rad/s. if one child is 1.0 m from the center and the other is 1.5 m from the center, what is their combined angular momentum?

Answer 1

The angular speed of the merry-go-round is
ω = 0.10 rad/s

The angular moment of inertia of a mass, m, at a radius, r, from the center of the wheel is
I = mr²

Therefore, the angular moment of inertia for the children are
I₁ = (25 kg)*(1.0 m)² = 25 kg-m²
I₂ = (25 kg)*(1.5 m)² = 56.25 kg-m²

The combined angular momentum is
ω(I₁ + I₂) = (0.10 rad/s)*(25 + 56.25 kg-m²)
               = 8.125 (kg-m²)/s

Answer: 8.125 (kg-m²)/s