Determining Mechanical Advantage
Many complex machines have an adjustable mechanical advantage. In this lab, you will learn how adjusting the mechanical advantage of a bicycle affects the bicycle's performance.
Problem How does mechanical advantage affect the performance of a bicycle?
Materials
board with two nails
4 thread spools, 3 with different diameters
rubber band
masking tape
multispeed bicycle (one or more per class)
meter stick
thick leather glove
Skills Measuring, Calculating
Procedure
Part A: Modeling the Mechanical Advantage of a Bicycle
On a separate sheet of paper, make a copy of the Data Table for part A.
Use a piece of masking tape to label each nail on the board. Label one nail Pedals and the other nail Wheel. To model the pedals and rear wheel of a bicycle, place a spool on each nail in the board and join the spools with a rubber band as shown.
Use a pencil to make a reference mark on the edge of each spool. These marks will help you observe the motion of the spools as they turn.
Measuring Use a ruler to measure the radius of each spool in your model. Record these measurements in your data table.
The pedal spool represents the pedals and the gears attached to them. The wheel spool represents the rear wheel and its gears. Using the reference marks, observe the wheel spool as you turn the pedal spool through five complete revolutions. Record the number of revolutions of the wheel spool in your data table.
Replace the wheel spool with a spool of a different diameter. Repeat Steps 3 through 5 for each diameter of wheel spool.
Calculating The ideal mechanical advantage (IMA) of a bicycle is equal to the distance the pedals move divided by the distance the rear wheel moves. For your model,
Calculate the mechanical advantage of each spool combination you used. Record these values in your data table.