Angular acceleration of a drill

[Dr_bug]

Homework Statement

A dentist's drill starts from rest. After 2.90 s of constant angular acceleration it turns at a rate of 2.20 x 10^4 rev/min.
(a) Find the drill's angular acceleration (in rad/sec^2).
(b) Determine the angle (in radians) through which the drill rotates during this period.

Homework Equations

The Attempt at a Solution

okay so for (a) I thought that I should convert the rev/ min to rad/sec first and got 2303.8 rad/sec and then I used: change in angular velocity/ change in time and got 886.09 but when I input this answer, webassign (thats how we submit homework) says I'm wrong... I don't know what else to try

 

[hage567]

Homework Statement

A dentist's drill starts from rest. After 2.90 s of constant angular acceleration it turns at a rate of 2.20 x 10^4 rev/min.
(a) Find the drill's angular acceleration (in rad/sec^2).
(b) Determine the angle (in radians) through which the drill rotates during this period.

Homework Equations

The Attempt at a Solution

okay so for (a) I thought that I should convert the rev/ min to rad/sec first and got 2303.8 rad/sec and then I used: change in angular velocity/ change in time and got 886.09 but when I input this answer, webassign (thats how we submit homework) says I'm wrong... I don't know what else to try

Are you using 2.9 s for your time? Check your division.

 

[Dr_bug]

Ahh Geez... thanks I was going crazy