RPM Lab

Precalculus students study the arclength formula S = r * theta relating linear distance/velocity to angular distance/velocity. In the image below, one student is running the program RPM on a Texas Instruments calculator with a photogate attached to the CBL while another student is spinning the bicycle wheel. A tongue depressor has been attached to the wheel to pass through the photogate. The program calculates the number of rpm's which the wheel has been spun. Students will then determine the linear speed of a point on the outside of the wheel.

A tongue depressor has been attached to the wheel to pass through the photogate. The program calculates the number of rpm's which the wheel has been spun. Students will then determine the linear speed of a point on the outside of the wheel.

In the image below, LHS precalculus teacher Jerel Welker is demonstrating and motorized pulley system. A sprocket on a motor has a belt attaching it to another sprocket, similar to that of a bicycle. The angular speed of the sprocket on the motor is measured using the rpm program and students are. Students are asked to determine the linear speed of the belt, the angular velocity of the rear sprocket, and the linear velocity of a point on the outside of the rear sprocket.