When Physics Class Demonstration Goes Wrong

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The discussion centers around a physics demonstration gone awry, leading to speculation about the teacher's job status and the identity of the person struck during the experiment. Participants share anecdotes about physics demonstrations, highlighting the risks involved and the potential for mishaps. One user describes a classroom experiment using a spinning tire to teach angular momentum, joking about intentionally misleading students. Another recalls a near-miss incident involving a bowling ball demonstration, where a professor almost injured himself while illustrating conservation of energy. The conversation touches on the balance between engaging demonstrations and safety, with references to famous physicists like Richard Feynman, known for his dramatic teaching methods. Overall, the thread reflects on the fine line between effective teaching and potential danger in physics demonstrations.
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Who said that it went wrong? I don't know what the goal of the experiment was, so maybe it was exactly what they wanted to do? :biggrin:
 
Absolutely! Physics teachers can be very sneaky.

In a satellite attitude control class I teach at work, I use a spinning tire and let all the students hold it and then try to change the orientation of the spin axis so they can actually feel angular momentum (gyroscopic stability). When I get to a student I don't like, I tell him to just jerk the tire to the left!

Unfortunately, I eventually teach them about precession maneuvers and it sometimes dawns on the student that that initial demonstration may not have been an accident. But that's okay. Their lips are still so sore that they don't say much about it anyway.
 
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Greg Bernhardt said:
oh my! That was difficult to watch! Terrible aim!

Or perfect aim? Do you have any idea how difficult it is to pull that off while making it look like an accident?
 
In one of my big intro Physics classes in undergrad, the prof wanted to demonstrate conservation of energy and pendulum motion. He had a bowling ball that was suspended from the high ceiling with a thin rope -- he pulled the bowling ball to one end of the lecture stage and climbed a few steps up an A-frame ladder. He held the bowling ball to his nose and said "Now you will see that when the ball comes back it will stop a little short of my nose because of the small losses due to air resistance." he released the ball, it swung across the lecture stage, turned around and came back, and almost broke his nose. I'm guessing he just didn't hold his position very still while the bowling ball was swinging out and back to him... :woot:
 
berkeman said:
In one of my big intro Physics classes in undergrad, the prof wanted to demonstrate conservation of energy and pendulum motion. He had a bowling ball that was suspended from the high ceiling with a thin rope -- he pulled the bowling ball to one end of the lecture stage and climbed a few steps up an A-frame ladder. He held the bowling ball to his nose and said "Now you will see that when the ball comes back it will stop a little short of my nose because of the small losses due to air resistance." he released the ball, it swung across the lecture stage, turned around and came back, and almost broke his nose. I'm guessing he just didn't hold his position very still while the bowling ball was swinging out and back to him... :woot:

Professor Clint Sprott at UW-Madison had this as one of the demo in the now-famous "Wonders of Physics" show. He actually put his chin on a folding ladder so that his face doesn't move.

I had him as an instructor when I was there, and he didn't do any demo in his class, unfortunately.

Zz.
 
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Here's how you do it:

 
  • #10
I'm pretty sure Feynman originated the bowling ball demonstration:

The lectures themselves were brimming with inspiring “showbiz demonstrations” as his friend Richard Davies describes them. Most memorably, Feynman used to set up a heavy brass ball on a pendulum, send it swinging across the room, and then wait for it to swing back towards him. Students would gasp as it rushed towards his face, but Feynman would stand stock still, knowing it would stop just in front of his nose.
http://www.telegraph.co.uk/culture/10036024/Richard-Feynman-Life-the-universe-and-everything.html

Couldn't find a source for this, but I think the sledgehammer to the balls demonstration was originated by Vlad the Impaler.
 
  • #11
Greg Bernhardt said:
oh my! That was difficult to watch! Terrible aim!
I was thinking that he was going to get hit in the head. That would have really hurt and could have killed him. Amazing stupidity. :wideeyed:
 
  • #12
The guy on the floor seems to be wearing safety goggles - what could go wrong!
 
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