2.
17.42 A disc drive is driven by a friction driver, as shown
in Fig. P17.42. Initially, the angular velocity of the disc is
$ \omega_2 $ [rad/s], clockwise, and that of the driver is $ \omega_1 $ [rad/s],
counterclockwise. Derive a formula for the constant an-
gular acceleration $ \alpha_1 $ [rad/s$^2$] that the driver must have to
increase the disc's angular speed from $ \omega_2 $ to $ \omega_3 $ in time t
[s]. Express the result in terms of $ r_1 $, $ r_2 $, $ \omega_1 $, $ \omega_3 $, and t.