Indiana Science HS-PSII-1.2
The Standard
For a system consisting of two objects with no net external forces applied, qualitatively and quantitatively analyze a two-dimensional interaction (i.e., collision or separation) to show that the total linear momentum of the system remains constant
Indiana Academic Standards for Science (2023) · Energy and Momentum in Two Dimensions
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students use mass and velocity to find each object's momentum before and after a collision or separation. They add the horizontal and vertical parts separately to check whether the pair's total momentum stays the same.
What Mastery Looks Like
- A student keeps track of direction when adding momentum in each axis. Given one missing final velocity, they can find both of its components and explain why an object's momentum can change while the pair's total does not.
Common Misconceptions
- Students may add speeds instead of velocity components, or treat leftward motion as positive. Some expect each object's momentum to stay fixed, or think kinetic energy must stay the same in every collision.
How to Assess It
- Exit ticket: Two 1 kg pucks start with velocities (2, 0) m/s and (0, 2) m/s. After they collide, one moves at (0, 1) m/s. Find the other's velocity and show the momentum totals in both directions.
Lesson moves
Ways to Teach It
Slide two coins into an angled collision on a smooth desk; use phone video and a ruler to estimate velocity components before and after.
Show arrows for two pucks before and after impact; ask, “Why can one puck lose horizontal momentum while the pair keeps its total?”
Give pairs four collision cards with masses and velocities; have them calculate missing velocity components, then swap cards to check both totals.
Show a slow-motion clip of billiard balls colliding at an angle; students draw momentum arrows and predict each ball's path.
Free download
Printable HS-PSII-1.2 Worksheet
A ready-to-print activity worksheet aligned to HS-PSII-1.2, with an answer key for the teacher on its own page. No account needed.
PDF, US Letter, prints cleanly in black and white.
Download the worksheetKeep exploring
Related Standards
- HS-PSII-1.3
For a system consisting of two objects moving in two dimensions with no net external forces applied, apply the principles of conservation of linear momentum and...
- HS-PSII-1.1
For a system consisting of a single object with a net external force applied, qualitatively and quantitatively predict changes in its linear momentum using the ...
Turn this exact standard into a lesson
Grade, subject, topic, and the complete standard are prefilled. Create one free, no account needed.
Also for this standard:Make a WorksheetMake a QuizMake a Sub Lesson