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Calculate the centripetal acceleration of a point 7.50 cm from the axis of an ultracentrifuge whose angular velocity works out to 7854 rad/s.
AAbout 4.63 x 10^6 m/s^2
BAbout 5.89 x 10^4 m/s^2
CAbout 4.63 x 10^4 m/s^2
DAbout 1.05 x 10^8 m/s^2
Answer & Solution
Correct answer: A. About 4.63 x 10^6 m/s^2
1. Centripetal acceleration in terms of angular velocity is ac = r * omega^2.
2. Convert the radius to meters first, since 7.50 cm = 0.0750 m.
3. Substitute the values: ac = (0.0750 m)(7854 rad/s)^2.
4. Squaring 7854 rad/s gives about 6.169 x 10^7 rad^2/s^2, and multiplying by 0.0750 m gives ac = 4.63 x 10^6 m/s^2.
5. Dividing this by g = 9.80 m/s^2 gives a ratio of about 472,000, confirming the acceleration is roughly 472,000 times g, far larger than any of the other listed magnitudes.
6. 5.89 x 10^4 m/s^2 and 4.63 x 10^4 m/s^2 are each off by a factor of 100 from a decimal slip in the radius conversion, and 1.05 x 10^8 m/s^2 comes from squaring the radius instead of the angular velocity.
_Source: OpenStax College Physics (CC BY 4.0), Ch 6 "Uniform Circular Motion and Gravitation", section 6.2 Centripetal Acceleration_
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