Momentum is always conserved- even by toys!
1. Find two nearly identical toy cars that roll easily
2. Make two loops out of masking tape (sticky side out). Put one loop on the front of one of the cars and the other loop on the back of the other car.
3. Place the care that has tape on the back on the floor. Gently roll the other car into the back of the stationary car. Was momentum conserved? How do you know?
Predict what will happen if you put masking tape on the fronts of both cars and roll them at each other with equal speed. Will momentum be conserved in this case? Test your prediction.
Before you hear the details of this law, you should know that the word conservation means something different in physical science than in everyday usage. In everyday usage, conservation means saving resources. You might conserve water or fuel for example. In physical science, the word conservation refers to conditions before and after an event. A quantity that is conserved is the same after an event as it was before the event.