Electric toothbrushes can be effective in removing dental plaque. One model consists of a head 1.10 cm in diameter that rotates back and forth through a 70.0 degree angle 7600 times/min. The rim of the head contains a thin row of bristles.(adsbygoogle = window.adsbygoogle || []).push({});

Part A: What is the average angular speed in each direction of the rotating head, in rad/sec?

(140degrees)(pi/180) = 2.44 rad/rev

w = (7600 rev/min)(1min/60sec)(2.44rad/1rev) = 310 rad/sec

Part B What is the average linear speed in each direction of the bristles against the teeth?

A little unsure of

v = rw

v = (.006m)(310rad/sec)

v = 1.85 m/s

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Linear & Angular Quantities

**Physics Forums | Science Articles, Homework Help, Discussion**