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Re: arons and dry ice



Here are some ideas that come to mind - but I don't teach so I haven't
tried them with students.

1. Discuss the motion of a bowling ball in a bowling alley. Bring a
bowling ball in to school and roll it down the hall. (We've done this at my
company.) Slowly push a bowling ball and note the resultant motion.
Examine the motion of a pushed bowling ball on rougher and rougher
surfaces.

2. Place a heavy bucket of rocks on a 10 speed bike and push the bike to
accelerate it. Place a scale where you push it so that you can measure the
force. Measure the speed as a function of time as you push it.

3. Push a car to accelerate it. Have a number of students each push on a
scale that is on the car (the scale is in the vertical direction).

4. Discuss what a year is. Discuss the constancy of the year. Discuss
what that might mean concerning the motion of bodies in the absence of
friction.

5. Discuss the motion of space probes.

6. Discuss videos of objects being thrown in the space shuttle.

Yes there are details here such as the rotational kinetic energy of the
bowling ball and the "free falling" motion of orbiting bodies, but the
essence of force and motion is there.


At 4:33 PM -0700 10/8/2002, Justin Parke wrote:
I read in arons (sorry don't have the specific reference) earlier today the
section on introducing Newton's laws and specifically the concept of inertia
and the effects of forces on a body's motion. He recommends a 50 lb piece of
dry ice on a sheet of glass. Has anyone done this? How big is the sheet
of glass? How big is 50 lbs of
dry ice? I am not sure where I will obtain these things but the idea is a
great one...much better than 1 dimensional pasco carts or even an air table
(since the pucks have such low mass). Are there similar but easier things
folks have tried?

Larry Woolf,General Atomics,San Diego, CA 92121; Phone: 858-526-8575; FAX:
858-455-8568

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.