Reference: M88
Category: Mechanics
Purpose: Demonstrates conservaiton of momentum with a less intuitive setup.
Description: There is a hinge in the pan of a spring balance, which should be opened to about 45 ○. A thread attaches the upper leaf of the hinge to a hook that you can probably hold in your hand. Burn the thread. The upper leaf acquires downward momentum, so the rest of the apparatus acquires upwards momentum and the index jumps upwards briefly. The motion stops when the upper leaf hits lower leaf.