HS-PS2-2 | Conservation of Momentum

Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system.

Clarification statement: Emphasis is on the quantitative conservation of momentum in interactions and the qualitative meaning of this principle.

Assessment boundary: Assessment is limited to systems of two macroscopic bodies moving in one dimension.

Assessment

What assessment of HS-PS2-2 might look like on a NY state exam.

Exam	Cluster	Question
June 2026	From Astro Blaster to Supernova	Question 38

Performance Level Descriptions

PLDs communicate the knowledge and skills expected of students to demonstrate proficiency in each Learning Standard. NYS assessments classify student performance into one of five levels.

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Level 1: Given data and/or a model, use a mathematical representation for momentum to identify the mass, or the momentum (with or without direction), or the velocity/speed of an object.

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Level 2: Given data and/or a model, use a mathematical representation to determine the total momentum, with or without direction, of a system of objects before or after an interaction when there is no net force on the system.

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Level 3: Given data and/or a model, use a mathematical representation for the conservation of momentum to determine the mass and/or velocity of an object before or after an interaction between two objects when there is no net force on the system.

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Level 4: Use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system.

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Level 5: Collect and analyze data and use mathematical representations to support the claim that the total momentum of a system of objects is conserved when there is no net force on the system.

Vocabulary

Terms from the Physics Glossary that come from this standard or from the released exam questions that assess it.

From this standard

boundaries of a system
boundary
claim
conservation of momentum
direction
force
frame of reference
initial conditions
interaction
macroscopic bodies
mass
mathematical representation
momentum
net force
object
one dimension
qualitative
quantitative
speed
support (a claim)
system
system of objects
total momentum
velocity

From released exam questions

before and after collision – June 2026
collision – June 2026
computer simulation – June 2026
law of conservation of momentum – June 2026
rebound – June 2026
refute – June 2026
significant digits – June 2026
simulation – June 2026

Resources

Examples and discussion of resources for the learning, teaching, and assessment of HS-PS2-2.

This section could be expanded upon. You can help out by adding to this section.

NGSS Dimensions

Performance expectation HS-PS2-2 was developed using the following elements from the NRC document A Framework for K-12 Science Education:

Science and Engineering Practices

Using Mathematics and Computational Thinking
- Use mathematical representations of phenomena to describe explanations.

Disciplinary Core Ideas

PS2.A: Forces and Motion
- Momentum is defined for a particular frame of reference; it is the mass times the velocity of the object.
- If a system interacts with objects outside itself, the total momentum of the system can change; however, any such change is balanced by changes in the momentum of objects outside the system.

Crosscutting Concepts

Systems and System Models
- When investigating or describing a system, the boundaries and initial conditions of the system need to be defined.

Page contributors: Caroline Leonard, Conrad Richman

Physics | HS. Forces and Interactions