Question

A disk rotates with constant angular acceleration. The initial angular speed of the disk is 2π rad/s. After the disk rotates through 15π radians, the angular speed is 13π rad/s.
a) What is the magnitude of the angular acceleration?
(b) How much time did it take for the disk to rotate through 15π radians?
(c) What is the tangential acceleration of a point located at a distance of 8 cm from the center of the disk?

Answer 1

\[\large \omega_i = 2\pi {\frac {rad} s} \]
\[\large \omega_f = 13\pi {\frac {rad} s} \]
\[\large \theta_f = 15\pi { {rad} } \]
\[\large \omega_f=\omega_i+\alpha t\]

Answer 2

@vegeto no time was given?

Answer 3

Ok, it looks like the first thing you'll need to do is solve for the angular acceleration.
\[\huge \omega_f^2=\omega_i^2+2\alpha(\theta_f-\theta_i)\]

Once you have the angular acceleration, you can find the time.

Tangential acceleration is simply
\[\huge a=r\alpha\]
Just make sure your units make sense.