Not calc based! tangential and angular acceleration

[darlagatsch]

Homework Statement

a disk rotates with constant angular accel. the initial angular speed of the disc is 2pie rad/s. After the disk rotates through 10pie rad, the ang speed is 7pie rad/s.

Homework Equations

a. what is the mag of the angular accel?

The Attempt at a Solution

alpha=delta omega/delta time
omega=delta theta/delta time
etiher or both?

 

[PhanthomJay]

Homework Statement

a disk rotates with constant angular accel. the initial angular speed of the disc is 2pie rad/s. After the disk rotates through 10pie rad, the ang speed is 7pie rad/s.

Homework Equations

a. what is the mag of the angular accel?

The Attempt at a Solution

alpha=delta omega/delta time
omega=delta theta/delta time
etiher or both?

the first one has 2 unknowns and the second one is wrong...why not try one of the other kinematic equations for constant angular acceleration.....the one that relates omega with alpha and theta?

 

[darlagatsch]

i have no idea! HELLLP

 

[PhanthomJay]

i have no idea! HELLLP

Well you seem to have known somehow that alpha=delta omega/delta time, how did you know that? You can find the equations on the link below, 4th slide:

http://www.colorado.edu/physics/phys2010/phys2010_fa11/LectureNotes/phys2010_fa11_lecture28.pdf [Broken]

You should first learn, understand, and memorize the motion equations for translational motion.