Question

A CD with a diameter of 120 millimeters rotates a rate of 45 revolutions per minute. Find the linear speed of the CD in millimeters per minute. And find the angular speed of the CD in radians per minute

Answer 1

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Answer:

• 16,965 mm/min
• 90π ≈ 282.7 radians/min

Step-by-step explanation:

The circumference of the CD is ...

  C = πd

  C = π(120 mm) ≈ 376.99 mm

This is the distance a point on the edge of the CD will travel when making one revolution. It will travel 45 times this far when making 45 revolutions:

  (376.99 mm/rev)(45 rev/min) ≈ 16,965 mm/min

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There are 2π radians in each revolution, so the angular speed is ...

  (2π rad/rev)(45 rev/min) = 90π rad/min ≈ 282.7 rad/min