Science Quiz |The Slinky Drop

A favorite site of mine is Veritasium on YouTube. A short video is produced regularly on some simple questions about the natural world. They show the phenomenon clearly, often with slow motion video. The public is often asked what they think will happen. This one uses an object most people have played with as a child or an adult. It’s fun to make them walk down a stairs. But, there are many other ways to play with them.

Hold a slinky so it hangs down stretched out and still.

Let go of the top end so it starts to fall.

Question: What happens to the bottom end when you drop the top end?

Go ahead and watch the video below to see how the question is posed by Prof. Rod Cross of the University of Sydney. Make sure you understand how it will be done. Please choose an answer from their choices on screen. Replay as needed to see them again.

Yes…this will be on the final exam.

In case you didn’t click on a choice in the previous video. Here is the result.

How did you do? Were you surprised? What do you think will happen if a tennis ball is hung from the bottom to make it heavier than before?

Here is the result video if you didn’t click on the screen choices.

Prof. Cross skilfully uses the phenomenological approach.

  • Clearly explain what you plan to do.
  • Ask for an investment into a prediction of the expected result.
  • Show the phenomenon.
  • Show the phenomenon again if needed. Talk it over. Answer questions.
  • Present a small variation to the phenomenon.
  • Ask once more for a prediction.

In 1968, a group of physics teachers founded the Illinois State Physics Project (ISPP).

ISPP is a loose organization of High School, College, and University Physics Teachers in the Chicago Area who meet once a month , except November and July and August, at a host school to discuss teaching methods, lecture and lab demonstrations, and teaching techniques. We emphasize the use of phenomena to engage the student, so the presentations usually involve activities.

One of the founders was Prof. Emeritus Earl Zwicker of the Illinois Institute of Technology. The group met monthly to share ideas for teaching physics. Members tried to keep their presentations to a short 5 or 10 minutes. These ‘take fives’ proved to be very popular and effective at spreading good ideas to other teachers. The ISPP group is still meeting. Due to the large distances to Chicago meeting places, two local groups called Physics West and Physics NorthWest also formed. The groups meet monthly throughout the school year. Thanks to the example of the ISPP group, thousands of physics students have been exposed to some of the highest quality instruction available.

I hope you found the videos excellent and engaging. Some people were very surprised by the results. How about you?


6 thoughts on “Science Quiz |The Slinky Drop

  1. That was very cool! And no, I didn’t predict the correct result. I thought both ends would approach each other. It was really interesting to watch myself being proven wrong – in slow motion!


    • They did a really good job presenting it. I doubt if you are alone in your choice. I hope to see some results in the poll.

      Thanks for being a good sport.


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