Alternate Impulse-Momentum Projects

Yesterday's Egg Drop Day was a near disaster. I definitely need an alternate project for this unit for classes that are either too disrespectful for me to ensure good behavior when we're outside the classroom or too scattered to heed instructions. This project needs to accomplish two major goals: to have students apply the relationship between impulse and momentum to a real world goal and to involve students in building and testing something of their own design.

So far, some of my colleagues and I have come up with a few ideas.

1. Throw something heavy at them and teach them how to extend the impact time in order to reduce the force. This succeeds at goal one, but not goal two, and comes with too great a potential for injury to a student.
2. Throw something heavy at something a student has constructed to protect something other than the student. This succeeds at both goals, but requires me to throw heavy objects seventy or more times in a day, which doesn't seem good for my shoulders.
3. Use a colleague's compressed air gun to launch something at something a student has constructed to protect, say, an egg. This succeeds at both goals, but there's the pesky matter of aiming the gun properly so as to be able to hit the student's project on the first try, in order to get a class of over twenty students' projects tested within a forty-five minute class period.
4. Use a colleague's compressed air gun to launch something the student has constructed to protect, say, an egg, at a wall. This succeeds at both goals and solves the aim problem. It may present a problem of finding or constructing a suitable wall and adjusting the muzzle velocity of the air gun so that egg-survival is possible.

Using the compressed air gun presents an opportunity to make the project a bit more quantitatve, as well, since we could measure the muzzle velocity, the mass of the egg, and possibly even the force required to crack an egg, therefore calculate the amount of time needed to keep the egg safe. This would also give me an opportunity to talk about safety tolerances.