A disc of radius R=20 cm is rotating about its axis with an angular velocity ω=20 rad/s on a horizontal smooth surface. The linear speed of point C on the disc is:
Correct answer: D. 4 m/s
- A. 1 m/s
- B. 3 m/s
- C. 2 m/s
- D. 4 m/s
Explanation
Convert radius to meters r = 0.20 m. Linear speed v = r ω = 0.20 × 20 = 4 m/s. Hence option D is correct.
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About Angular and Linear Quantities
Rotational motion relates angular displacement, angular velocity and angular acceleration to linear displacement, tangential velocity and tangential acceleration through the radius. Questions use radians, v equals r omega and tangential acceleration, while distinguishing tangential velocity from centripetal acceleration and angular quantities from their linear counterparts.
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