# Learner lab record: Collision momentum and energy audit

Course: Mechanics and conservation laws

Name: ____________________  Date: ____________________  Group: ____________________

## Investigation question

Which quantities remain conserved when two carts collide, and what changes when they stick or rebound?

## Setup

Use the collision laboratory. Hold the two masses fixed while comparing an elastic case with a sticking case, then change one mass and repeat.

## Variables

| Variable | Role | Unit |
| --- | --- | --- |
| Cart masses | controlled, then independent | kg |
| Initial velocities | independent | m/s |
| Final velocities | dependent | m/s |
| Total momentum and kinetic energy | calculated | kg·m/s and J |

## Predict before changing controls

1. Predict the final direction of the system momentum.

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2. Predict which collision preserves kinetic energy and which transfers it into other forms.

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## Observation table

| collision type | m1 | m2 | p before | p after | K before | K after |
| --- | --- | --- | --- | --- | --- | --- |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |
|   |   |   |   |   |   |   |

## Analyze

1. Which before/after residual is closest to zero?

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2. Where does kinetic energy go in the sticking model?

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3. Why must the system include both carts?

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4. Name one external impulse that would weaken the comparison.

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## Evidence-bounded conclusion

Across ___ collision models, total momentum changed by ___ while kinetic energy changed by ___ because ___.

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