A2L Item 080

• Description: Find the final angular velocity when a bug on a rotating plate crawls to a new radius,
• Goal: Problem solving using conservation of angular momentum.
• Source: UMPERG
• Keywords: Mechanics, Conservation, Angular Momentum, Rotational Motion

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The question for students:

A bug walks on a freely rotating disk. Given: M_bug=0.05 kg, I_disk=0.03 kg-m2, R_disk=0.5 m, and ω_o= 2 rad/s when bug is 0.1 m from center. The bug crawls to 0.4 m from the disk’s center. The final ω is most nearly:

1. 1.6 rad/s
2. 1.2 rad/s
3. 1.0 rad/s
4. 0.8 rad/s
5. 0.5 rad/s
6. None of the above
7. Cannot be determined

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Commentary for teachers:

Answer

(1) This is a very traditional conservation of angular momentum problem. The only difficulty is due to the presence of extraneous information. Some students may use conservation of energy.

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