# Difficulty With Wording of a Problem

1. May 31, 2005

### verd

Hi. So, I don't quite understand EXACTLY what they're asking me here.
Problem statement:

A fan blade rotates with angular velocity given by $$\omega _{z}(t) = ( 5.10 rad/s) - ( 0.785 rad/s^3) t^{2}$$

a.) Calculate the angular acceleration as a function of time.

Alright, I understand the kinematic formulas for constant angular acceleration... But are they asking me for an instantaneous angular acceleration? ...I wouldn't know about how to go about that, being that I would need to take the derivative of the function but with respect to angular displacement...

What exactly are they looking for by saying, "angular acceleration"? Any suggestions as to how to begin?

Thanks, by the way.

2. May 31, 2005

### whozum

Angular acceleration is the time derivative of angular velocity.