Published on: Mon Mar 01 2010

What happens when an object is rotated in a circle? A) Vector radius B) Radius C) Vector Velocity D) radius again E) instantaneous velocity F) The change in the radius vector is equal to the second radius vector minus the first radius vector G) The change in the velocity vector is equal to the second velocity vector minus the first. H) Instantaneous velocity equals the change in radius over the change in time. I) The change in radius is equal to the magnitude of the radius times the change in theta. J) The change in Theta is equal to the change in the radius vector over the Radius magnitude. K) The change in Theta is equal to the change in velocity over velocity. L) Acceleration is equal to the change in velocity (direction) over the change in time, it is also equal to the velocity magnitude times the change in radius magnitude, over the Radius Magnitude times the change in time. Centrifugal acceleration is equal to velocity squared over Radius magnitude. Now we put these components together to start talking about Force. Centrifugal force equals mass times centrifugal acceleration, which is the same as mass times velocity squared over radius. This force must be provided by something, to keep the mass moving in a circle. Otherwise it will just fly off in a straight line. Examples of the force provider are Tension in a String, Gravity and Electrostatic force. We did some examples, of what happens when you swing a can over your head (on a string), What happens to Tarzan when he grabs a rope and jumps off a cliff, and how the rider of a Ferris wheel feels as it rounds the top. We thought about how water in a can stays in the can when it is swung overhead with enough force. And we finished up with looking at a conical pendulum.