20. Torque Illustrations

A bicycle wheel can be mounted on the lecture table so you can illustrate the effect on acceleration of exerting forces on it at various radii and in various directions. A crescent wrench is also supplied so you can illustrate how to produce the maximum torque on the nut holding the bicycle wheel. Another simple illustration of torque is to open the door to the lab at the front of the lecture hall and push on it at various radii from the hinge with your index finger. The crumpling of your finger indicates the larger forces needed at the smaller radii.

A more quantitative demonstration of torque uses the rotational acceleration device shown here. The spindle is fitted with a spool of twice the radius of the shaft so the falling weight acts at 2R. Two devices are available. Adjust the weights so the rotational inertia is the same, and compare the rotational acceleration of the devices with the falling weight acting at R and 2R.