Angular Speed of Electric Toothbrush Head: 795.49rad/s

[bigtymer8700]

Electric toothbrushes can be effective in removing dental plaque. One model consists of a head 1.10cm in diameter that rotates back and forth through a 70.0 angle 7600times/min . The rim of the head contains a thin row of bristles. its asking me the average angular speed in each direction of the rotating head.

w=7600times/min(1min/60s)6.28rad/1rev= 795.49rad/s

but it says I am wrong what am i doing wrong?

 

[mgb_phys]

It rotates through 70deg 7600 times /minute not a full circle.
so that's 70 * pi/180 radians in 60/7600 seconds.

It could also be double that if it means it goes +70deg then back to the start 7600 times a minute?

 

[bigtymer8700]

yea it would be double since its going back and forth thanks