Angular acceleration of a softball

[physics1234]

One method of pitching a softball is called the "windmill" delivery method, in which the pitcher's arm rotates through approximately 360° in a vertical plane before the 198 gram ball is released at the lowest point of the circular motion. An experienced pitcher can throw a ball with a speed of 89.0 mi/h. Assume that the angular acceleration is uniform throughout the pitching motion, and take the distance between the softball and the shoulder joint to be 75.1 cm.

I found 89mph= 39.783m/s and the angular speed to be 8.4310rev/s. How do I find the angular acceleration from this?

 

[OlderDan]

One method of pitching a softball is called the "windmill" delivery method, in which the pitcher's arm rotates through approximately 360° in a vertical plane before the 198 gram ball is released at the lowest point of the circular motion. An experienced pitcher can throw a ball with a speed of 89.0 mi/h. Assume that the angular acceleration is uniform throughout the pitching motion, and take the distance between the softball and the shoulder joint to be 75.1 cm.

I found 89mph= 39.783m/s and the angular speed to be 8.4310rev/s. How do I find the angular acceleration from this?

You will want the angular speed to be in radians per second. You need to use the equations of angular motion kinematics. These are directly analogous to the more familiar equations of linear kinematics

http://online.cctt.org/physicslab/content/PhyAPC/lessonnotes/rotationalmotion/kinematics.asp