Action Between Frames
The camera should not change the motion
A puck travels from at to at . A camera divides the same one-second history into equal time intervals.
If the camera records more frames, should the action of the motion itself change?
One motion, several measurements
The puck still travels from 0 to 1 in one second.
divides that same second more finely.
For equal slices, .
If a proposed action changes only because the camera took more frames, it is measuring the recording scheme—not only the motion.
Page 1 · Test the tempting score
Complete the tables here. Show calculus work on separate paper.
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First test the tempting score on the steady history . Complete the table. The physical motion is unchanged, so explain why the tempting score cannot be its action.
Each 1 1 1 2 4
Page 2 · Repair the score and take the limit
Complete the table here. Show calculus work on separate paper.
Each interval contributes speed squared × duration. The factor accounts for how long that speed lasts.
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Now use for . Show in one line that the corrected score equals 1 for every . Then complete the accelerating-history table for .
Interval speeds 1 1 2 4 -
In the limit of infinitely fine time slices, the sums become
Compute both histories' continuous actions. Compare them with the frame sums. Explain what changes under finer measurement and what stays attached to the history.
Normalization note: A fixed positive factor does not change comparisons; hid it in Lab 1.