The rotational inertia of a disk about its axis is 0.70 Kg. m2. When a 2.0-kg weight is added to its rim, 0.40m from the axis, the rotational inertia becomes:
Correct answer: D. 1.02 kg - m2
- A. 0.38 kg - m2
- B. 0.54 kg - m2
- C. 0.86 kg - m2
- D. 1.02 kg - m2
Explanation
The correct answer is 1.02 kg - m2. The initial rotational inertia of the disk is 0.70 kg m2. When a 2.0 kg mass is added at a radius of 0.40 m, the additional moment of inertia is calculated using Im = m × r2. Substituting the values gives Im = 2.0 kg × (0.40 m)2 = 0.32 kg m2. Adding this to the original inertia results in a total of 1.02 kg m2. The other options underestimate the impact of the added mass, leading to incorrect calculations of the total rotational inertia.
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