Angular momentum activities using a carpenter’s measuring tape

摘要

In my backyard, my seven-year-old grandson, Ben, and I discovered that a carpenter’s measuring tape with a spring-loaded return mechanism can be used to observe conservation of angular momentum for a non-isolated system. I used a Stanley 25’ PowerLock (Fig. 1) for the activities discussed in this note. When the tape is pulled out and released, the spring mechanism pulls the tape back into the body of the unit. As a result, there is an increasing angular omentum of the spring mechanism within the unit as the tape retracts. The result of this angular momentum can be observed with two activities.