# Learner lab record: Two-frame light-clock record

Course: Space, time, motion, and reference frames

Name: ____________________  Date: ____________________  Group: ____________________

## Investigation question

How can laboratory time and distance change while the clock's own spacetime interval stays fixed?

## Setup

Use the two-frame light-clock studio. Hold proper time fixed, vary v/c, and compare coordinate quantities with the recovered interval.

## Variables

| Variable | Role | Unit |
| --- | --- | --- |
| Relative speed v/c | independent | unitless |
| Clock proper time τ | controlled | µs |
| Laboratory time and distance | dependent | µs and km |
| Recovered interval cτ | invariant check | km |

## Predict before changing controls

1. Predict the laboratory distance at v=0.

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2. Predict what happens to γ as v approaches c.

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## Observation table

| v/c | γ | lab time | lab distance | recovered interval | cτ |
| --- | --- | --- | --- | --- | --- |
|   |   |   |   |   |   |
|   |   |   |   |   |   |
|   |   |   |   |   |   |
|   |   |   |   |   |   |
|   |   |   |   |   |   |
|   |   |   |   |   |   |

## Analyze

1. Which quantities depend on frame?

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2. Which two columns should agree in every run?

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3. Why is time dilation not an optical illusion?

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4. State the model's inertial-frame limitation.

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## Evidence-bounded conclusion

Although the laboratory measured ___ and ___, subtracting the spatial contribution recovered ___, equal to ___.

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