Physics Blog 7: Uniform Circular Motion

Uniform circular motion, though it may seem an abstract concept in class and on our worksheets, is actually all around us. It was even abundant during Homecoming Week. On the day to dress up as pirates and ninjas, I was a ninja equipped with a deadly pair of NUNCHAKU!! (the plastic kind you buy at Price Busters for like $1) I now realize that swinging my nunchucks over my head was creating UNIFORM CIRCULAR MOTION!!

It's hard to tell from the angle of the picture, but the foam nunchucks are probably swinging at a slight angle below the horizontal. This makes the center of rotation just a little below the top of the half I'm holding. The centripetal force is being provided by the tension in the string, which is clearly less than the string's maximum tension - otherwise it would break. The length of the string is also the hypotenuse of an imaginary right triangle, the horizontal leg of which is the radius of the circle of motion. If I knew the length of the string (L) and the angle below the horizontal (A), I could calculate the radius (r) using r = (cosA)/L. If I were also given the linear velocity of the nunchucks, I could calculate the angular velocity using v = rw. PHYSICS IS ALL AROUND US!! :D