When I was a grad student I taught an undergrad 101 level physics class. On one of the early tests I stopped the class 10 minutes before the end of the period I climbed on the lecture table and held one end of a slinky as high as I could reach, letting the other end dangle. I told them this was the last question on the test and they were to predict what would happen and describe the forces. About a third of them got it right. As the tests were being collected I climbed on the table again, held up the slinky and released it to a combination of applause and groans.
The week afterwards I showed them how to calculate the speed of light to reasonable accuracy with a microwave oven and a few bars of chocolate, but that is another story.
Here are two delightful videos with excellent photography. The first sets up the problem and the second shows the resolution:
It is all about critical thinking.
It is sad physics is taught the way it is. Waiting until the students have a bit of mathematical sophistication and then boring them to death starting out with static forces. But add a bit of motion and suddenly the world gets interesting. With the pre-meds it was fun to point out that doing something like holding a brick at arm's length and attempting to keep it still may mean that no work is being done on the brick, but if you examine what is going on in your muscles a good deal of work is taking place and it can be extremely fatiguing.
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