Great Balls and Fire! Smashing Steel Spheres with Video


Tami O'Connor, Educational Innovationsby:  Tami O’Connor

When two 1-pound, 2-inch diameter, chrome steel spheres are smashed together, enough heat is generated at the point of contact to burn a hole in ordinary paper!  This dramatic demonstration has been a favorite of students in every grade for as long as I have been teaching!

Smashing Steel Sphere Demo KitThere are a few considerations when allowing students (especially younger ones) to conduct this activity on their own…  First, the spheres are pretty heavy, so if they were either dropped on a foot or onto a nice tile floor, the result would not be good.  Also, be sure that the only thing between the spheres is paper or aluminum foil.  Fingers caught between the colliding spheres would not  be happy.  Finally, all participants should wear safety glasses, as it is not unusual for a small piece of paper to fly off after the spheres collide.

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Teaching Energy Using Dropper Poppers


Tami O'Connor, Educational Innovationsby: Tami O’Connor

One of the units I enjoyed most as a middle school teacher was the section on energy.  The many awesome hands-on experiments generated such a series of oohs and aahs that it made my already-enjoyable days even more enjoyable!  One of my favorites was a lesson that dealt with the Law of Conservation of Energy.  A consequence of this law is that energy cannot be created, nor can it be destroyed.  (The students would have already explored potential and kinetic energy before the following activity.)

I initiated this lesson reviewing what happens with energy in a closed system.  The students clearly remembered comparing the amount of potential energy to kinetic energy using the example that the height of a roller coaster’s first hill is always greater than the height of any of the remaining hills.  It is, of course, possible to have a little hill followed by a higher hill as long as the roller coaster is going faster at the top of the little hill than the next higher one.  The students were generally able to explain the transfer of energy including heat energy and sound energy in the overall system.

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