1. Which would have a greater moment of inertia, a thin ring or a solid disk? Bo

Question

1. Which would have a greater moment of inertia, a thin ring or a solid disk? Both have the same mass and radius. Explain.

2. The moment of inertia of a 4.0m long board pivoted at its center is 25kgm^2. Find the moment of inertia when it is used as a see-saw with two 50kg kids sitting 1.8mm from the pivot. (convert to MKS)

3. Weights are sometimes added to the arms of a boomerang. What effect would this have on the spinning of the boomerang? Where should they be placed for greatest effect? Please indicate the location and explain your reasoning.

Explanation / Answer

moment of inertia of the ring =mr^2

moment of inertia of solid disk = mr^2/2

so ring has greater moment of inertia

2.

I =25+(2*50*0.0018^2)=25.000324 kgm^2

3.

by adding weights its moment of inertia increases so angular speed decreases

for greater effect it should be placed at edges

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