Physics Jeopardy: What's the Question?

For "Journal Meeting", Benedikt is having us read this paper about Physics Jeopardy problems by Alan Van Heuvelen.

He has asked us to come up with one physics jeopardy question to share. Here's mine:


What do you think? What situation could this represent? What question might have been asked?

Challenge: A Good Chemistry Discussion Question?

Here, Ellen has laid down the challenge of coming up with a good chemistry question–one that will stimulate interesting discussions like the rainbow question . So I'm giving that challenge to all of us.

If you're reading this, consider doing one of the following in the comments:

• Let us know a good chemistry question you or a colleague has used
• Brainstorm one or two possible questions (just throw 'em out there, see if they stick)
  
• Toss out some topic areas that you think might be a rich possibility, and say why
  
• Contribute a question about chemistry that has intrigued you personally
  
• Suggest a demonstration, situation, or phenomena that might induce a good question
• Suggest some essential features of a good chemistry question
• React to someone else's contribution
• Invite a colleague or friend to contribute
  

To help maybe start us off, here is a chemistry-related question over at dy/dan that led me and several of my colleagues to dig in for a few hours. My office white board is full of drawings, equations, arithmetic, etc. If you wanna know how that question might go in a high school classroom, there's a gallery of student whiteboards about the question over at Newton's Minions.