(A) Angular Speed:

to find the angular speed in units of radian/seconds I know the radian measure of a circle which is 2pirad...

then 500 rev/60 secs x 2pirad/1rev

I get the answer 52.35 cm

but they are getting the answer 50pi/3?? I have no idea how they are getting that.

(B) Find the linear speed, in units of cm/sec.

C=2pi(45)

C=90pi

therefore 1 rev = 90picm

500 rev/60 sec x 90picm/1 rev

then I get the answer 2356.19 cm/sec

and they get 750 pi???

and for (C) All you have to do is divide by two which is obvious, and therefore it is 375 pi.

What am I doing wrong??? Please explain to me what angular speed is and what linear speed is? TYVM