Posted by George on .
Rotating initially at 1800 rpm, a wheel with a diameter of 74.0 cm is brought to rest in 11.0 s. Calculate the magnitude of its angular acceleration in radians/second^2

Physics 
drwls,
The wheel radius makes no difference. They want an ANGULAR acceleration (or, in this case, deceleration) rate.
So, convert 1800 rpm to radians/s (which you surely know how to do) and divide the result by 11.0 seconds.
You should strictly put a minus sign in front of the number, to indicate deceleration. 
Physics 
George,
so do you not need the diameter for anything?

Physics 
drwls,
If you don't need the radius, you don't need the diameter