A CD has a diameter of 12.0 cm.If the CD is rotating at a constant angular velocity of 20.0 radians per seconds,then the period of the rotational motion is
A) 0.314 s.
B) 0.441 s.
C) 0.582 s.
D) 0.698 s.
E) 0.750 s.

Question

Quizplus · Accepted Answer

The angular velocity is given by ω = Δθ/Δt, where Δθ is the angle rotated in radians and Δt is the time taken for that rotation.

In one revolution, the angle rotated is 2π radians. Therefore, the time period for one revolution is given by T = Δt = Δθ/ω = 2π/ω.

The radius of the CD is 6.0 cm, so the circumference is 2πr = 12π cm. Therefore, the distance travelled in one revolution is 12π cm.

If the CD is rotating at a constant angular velocity of 20.0 radians per second, then the time period for one revolution is T = 2π/ω = 2π/20.0 = 0.314 seconds.

A CD Has a Diameter of 12