Exam-style question
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If a solid cylinder has a moment of inertia given by I = 0.5 * m * r^2, what happens to the moment of inertia if the radius is tripled?.
- A.It remains the same.
- B.It triples.
- C.It increases by a factor of nine.
- D.It decreases by a factor of three.
Model answer
What a good answer should say
- It increases by a factor of nine.
Explanation
Why this works
Using the formula I = 0.5 * m * r^2, if the radius (r) is tripled, the moment of inertia becomes I = 0.5 * m * (3r)^2 = 0.5 * m * 9r^2, which shows it increases by a factor of nine.
Common mistake
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