Sunday, September 30, 2012

The Newtonian Shot in high-speed

Two dart guns are fired straight downward at the same time. But the darts have been modified. One dart has a cork ball attached. The other has a steel ball attached. Which one hits first?

In class, we engage in a guided think-pair-share discussion. The guiding document can be found here:

The Newtonian Shot

I generally get good arguments for the light dart hitting first and for a tie. I'm lucky to have such engaged students!

Only after all arguments have been expressed and represented do I proceed with the demo. In class, I shoot the darts from guns suspended from a support bar structure attached to a ceiling I-beem.

For high-speed video goodness, I shot the pair outside in the blazing late afternoon light in sunny Sacramento.

Here's the 600-fps clip. Enjoy that cork ball bounce!

Here's the 1200-fps clip.

You might reasonable worry about finding the type of spring-loaded dart gun that works for this demo. You need a hard stick dart—Nerf darts or soft rubber darts simply won't do. They seemed to be available everywhere when I was a kid. But safety worries and lawsuits made them an endangered species. Fortunately Arbor Scientific is able to get them.

Arbor Scientific Dart Gun

1 comment:

AlanCalac said...

Thanks! I use this demo and having the high speed videos was helpful in convincing some skeptical students.

There is an updated ArborSci link for the dart gun: ArborSci