Problem 2)
What happens when coin A collides with coin B?
Predictions
A. A and B stick together and move as one.
B. B travels to the right and A follows it at a slower rate.
C. A stops and B travels to the right.
D. A and B move in opposite directions.
E. Other
In this prediction problem, the students were free to draw on the result of the previous experiment or ignore it.
The distribution of opinions concerning the outcome of the problem above was as follows:
A. 0 students
B. 8 students
C. 27 students
D. 2 students
E. 0 students
Reasons for the Predictions
C. All the energy from A will be transferred to B.
D. Both coins change shape and then return to their original state.
B. Some of the energy from A is transferred to B, but some remains in A causing it to continue moving to the right.
Result of the Experiment
The velocities of the two coins are exchanged.
Problem 3)
What happens when a 1 yen coin of mass 1 gram collides with a 10 yen coin with a mass approximately 4 times larger?
A. The 1 yen coin will bounce back and the 10 yen coin will move to the right.
B. The 1 yen coin will bounce back and the 10 yen coin won't move.
C. The one yen coin will stop and the 10 yen coin will move to the right.
The distribution of opinions concerning the outcome of the problem above was as follows:
A. 4 students
B. 29 students
C. 1 student
Result of the Experiment: A is correct.
In Problem 1, the coffee can moved slightly. The problem is straight forward up to this point. Now we continue with the next problem:
Problem 4) A 10 yen coin collides with four 10 yen coins. Will the outcome for the first 10 yen coin be the same as in Problem 3?
A. The same
B. Not the same
The result of the experiment was B. Why was this? Did the four 10 yen coins combine as a unit and repel the single 10 yen coin?
The next problems involved collisions with the four 10 yen coins fixed together with cellophane tape and collisions with 22 coins stacked on top of each other as well as others. In the first case, did the single 10 yen coin collide only with the coin at the leading end of the fixed group of ten yen coins, or did it collide with all of them as a group?
One might say that it could be thought of either way, but in the case where the single coin collides with the others as a group, it bounces back where as when it collides with only the leading coin of the group it stops. In other words the results differ depending on whether the single coin collides with the others as a whole or with only the leading coin of the group. Therefore it is not correct to say that one can think of it either way. Conversely, looking at the result of the experiment, it becomes clear whether the single coin collided with the group as a whole or only with the leading coin of the group. Thus far, this has not been addressed in Physics education, but it is of vital importance.
From this point on however, problems which involve predictions of an experiment based on the results of a previous experiment will be put forth in order to answer the question of what collided with what.
Lastly, as a conclusion we will look at the "Superball experiment" conceived by the American Harter.
