how do i find the angular acceleration?? what equation do i use?

Question

A dentist's drill starts from rest. after 3.2 seconds of constant angular acceleration, it turns at a rate of 2.51 * 10^4 rev/min.

1) find the drill's angular acceleration.
2) determine the angle (in radians) through which the drill rotates during this period.

Answer 1

first, convert the angular speed to rad/sec

25100*0.1047
2628 rad/sec

using
w=alpha*t
2628=alpha*3.2
alpha=821 rad/s^2

knowing w, compute th
th=.5*alpha*t^2
th=.5*821*3.2^2
th=4204 rad

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