College Physics
posted by Angela on .
Some bacteria are propelled by motors that spin hairlike flagella. A typical bacterial motor turning at a constant angular velocity has a radius of 1.1x108m, and a tangential speed at the rim of 2.0x105 m/s. (a) What is the angular speed (the magnitude of the angular velocity) of this bacterial motor? (b) How long does it take the motor to make one revolution?
I was able to answer a) but I am not sure what equation to use for part b. Below is what I have calculate. A helpful nudge in the right way would be great!
VT = 2.0x105 m/s
r = 1.1x108m
w = 1818.18 rad/s
a)w = (2.0x105 m/s = 1.1x108m)t

a) angular speed = w = V/R
= 2*10^5/1.1*10^8 = 1818 rad/s
b) Period = (2 pi)/w = 3.36*10^3 s 
Thank you!
You answer is correct. My calculator is giving me 0.00345. I am not sure why. Do you think that it could be a setting that I need to change? 
Never mind  I figured it out.
Thanks for your help! 
my calculator is giving me 0.00345. How did you figure it out?