I thought about this a bit and came up with the following:

1. “Galileo’s biggest problem in studying the motion of a falling body was with the measurement of
short time intervals.” (Illustrate with a cup dripping water drops at a constant rate.)

2. “He could use the constant dripping of water from a small hole drilled in the bottom of a cup to
measure times that were relatively short, but still much longer than the fall time of a body dropped
from a reasonable distance.” (Add to illustration some picture of a body falling from some
distance in a time much shorter than the time between drops.)

2_mod  He could use the constant dripping of water in a water clock to measure times that were relatively short, but still much longer than the fall time of a body dropped from a reasonable distance.

3. “He realized he needed to slow the motion of the falling body, so he decided to allow the body
to roll down an inclined plane rather than drop freely.” (Remove freely falling body and insert ball
rolling down plane with several water drops falling during the time needed to reach bottom.)

4. “By so doing, Galileo discovered the ball dropped by an ever increasing amount where in the first
time interval was one unit of length, the second was three length units, and so on.

4._mod “By so doing, Galileo discovered the ball rolled by an ever increasing amount where in the first
time interval was one unit of length, the second was three length units, and so on.

5. “By increasing the angle of the plane, he found that while the ball rolled faster when the angle was
increased, the amount it dropped followed the same pattern.” (Increase the plane angle once or
twice.)


5_mod. “By increasing the angle of the plane, he found that while the ball rolled faster when the angle was
increased, yet the amount it rolled followed the same pattern.” (Increase the plane angle once or
twice.)

6. “He reasoned that if the angle were increased to 90 degrees, the same pattern would occur and
the motion of a freely falling body would be quantitatively described.” (Increase angle to 90.)



6_mod. “He reasoned that if the angle were increased to 90 degrees, the same pattern would occur and
the motion of a freely falling body would be quantitatively described.” (pan to tower and drop?)


Galileo’s biggest difficulty in studying the motion of a falling body was with the measurement of
short time intervals.
7s
He could use the constant dripping of water in a water clock to measure times that were relatively short, but still much longer than the fall time of a body dropped from a reasonable distance.
17s
He realized he needed to slow the motion of the body, so he decided to study bodies rolling down
an inclined plane.
25s
In these studies, Galileo discovered the ball rolled by an ever increasing amount where in the first
time interval the body rolled one unit of length, the second three units, the third five units, and so on.
38s
By increasing the angle of the plane, he found that while the body rolled faster, the amount it rolled in successive intervals followed the same pattern.
46s
He reasoned that if the angle were increased to 90 degrees, the same pattern would occur and
the motion of a freely falling body could be quantitatively described.
56s