Using experimental evidence, simulations, and computational models, students will calculate the momentum of two-object systems and construct an evidence-based explanation of when total momentum is conserved.

Digital-skills objective

Students will manipulate a digital simulation and computational model, collect and compare outputs from multiple representations, identify at least one model assumption, and communicate a source-linked claim using digital evidence.

Student checklist

By the end of the center, you will submit:

1. An initial prediction and Notice–Wonder–Need response

2. Evidence from three simulated collisions

3. Two scenarios tested in the Voilà model

4. One identified assumption from the Jupyter notebook

5. A response to the NASA DART investigation

6. A final claim–evidence–reasoning explanation and peer response

Watch the video once without calculating. Focus on the motion of both tennis balls before, during, and after each collision.

Driving question: How can the motion of each tennis ball change while something about the entire system remains unchanged?

Notice: Describe two things you observed.

Wonder: Pose one question raised by the demonstration.

Need: Identify the measurements needed to test momentum conservation quantitatively.

The astronaut states that momentum is conserved. Does watching the motion alone establish that claim? Explain what additional evidence would make the conclusion more convincing.

Open the Collision Lab simulation and select the one-dimensional mode. Establish rightward motion as positive.

Test these three cases:

• Two equal masses, with one object initially at rest

• Two unequal masses

• A completely inelastic collision in which the objects stick together

For each case, record:

• Each object’s mass

• Each initial velocity

• Total initial momentum

• Each final velocity

• Total final momentum

• Whether kinetic energy was also conserved

Post one screenshot or image of your most surprising trial. In the accompanying text, explain why the individual objects’ momenta changed while the system momentum did or did not remain constant.

In the model, Cart 1 begins on the left and Cart 2 begins on the right. Rightward velocity is positive, and leftward velocity is negative.

Before selecting “Run collision and reveal results”:

1. Choose the mass and initial velocity of each cart.

2. Select the collision type.

3. Predict the final velocity of both carts.

4. Explain your prediction using mass, velocity, direction, and total system momentum.

After revealing the results:

1. Play or drag through the collision animation.

2. Compare each cart’s momentum before and after the collision.

3. Compare the total system momentum before and after the collision.

4. Determine whether the system’s kinetic energy was conserved.

5. Identify one assumption built into the model.

Complete both investigations below.

Directions

Read or view the DART resource, then answer:

1. How could a relatively small spacecraft change the motion of a much more massive asteroid?

2. Why was the spacecraft’s velocity important?

3. What objects should be included in the system?

4. What evidence showed that the asteroid’s motion changed?

5. How might material ejected during impact affect the momentum transfer?

Write or record a response using the concepts of:

• System

• Mass and velocity

• Direction

• Momentum transfer

• Total system momentum

• Evidence from at least two learning objects

Required structure

Claim: State whether the student’s statement is correct.
Evidence: Refer to calculations, simulation results, video observations, or model outputs.
Reasoning: Explain how the evidence supports your conclusion using conservation of momentum.

At least one peer response required:

Respond to one classmate by identifying one strength in the explanation and posing one question that could make the reasoning more precise.

• Cart 1 mass and initial velocity

• Cart 2 mass and initial velocity

• Both final velocities

• Initial and final system momentum

• Initial and final kinetic energy

1. A screenshot of one completed collision

2. The input values you selected

3. The collision type

4. A response to this question:

How can the momentum of each individual cart change while the total momentum of the two-cart system remains constant?

Also identify one assumption of the model and explain how violating it might affect an actual cart experiment.

Open the notebook in Colab and save your own copy. Run the cells from top to bottom.

As you work:

1. Identify the two lines where p=mv appears.

2. Locate the line that adds the two carts’ momenta.

3. Change one mass or velocity and rerun the calculations.

4. Explain why negative velocity produces negative momentum.

5. Identify one assumption built into the model.

6. Compare what is visible in the notebook with what is visible in the Voilà application.

Submit a comment containing:

• The two Python lines that calculate individual momentum

• The line that calculates total system momentum

• The variable you changed and its new value

• The resulting total momentum

• Your explanation of negative momentum

• One model assumption and its limitation

• Two or three sentences comparing the notebook with the Voilà interface

Each student must:

• Respond to the claim.

• Define the system.

• Refer to evidence from the simulation or model.

• Include at least one calculation.

• Explain the distinction between individual and system momentum.

• Respond constructively to one classmate.

Students may respond orally as an alternative to writing.