HS-PS3-5: Forces and Energy in Fields
Also called NGSS HS-PS3-5 · Topic: Energy · Physical Science
The Official Wording
Develop and use a model of two objects interacting through electric or magnetic fields to illustrate the forces between objects and the changes in energy of the objects due to the interaction.
Clarification statement: Examples of models could include drawings, diagrams, and texts, such as drawings of what happens when two charges of opposite polarity are near each other.
Assessment boundary: Assessment is limited to systems containing two objects.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-PS3-5 Means in Plain English
Students draw and use models of two magnets or two charges acting on each other through a field. The models show the push or pull each object feels and how the energy stored in the field changes as the objects move closer or farther apart.
Models stay with just two objects, and they can be drawings, diagrams or written explanations. This builds on MS-PS2-5 and MS-PS3-2, pairs with the force math in HS-PS2-4, and prepares for electromagnetic induction in HS-PS2-5.
HS-PS3-5 I Can Statements
- I can draw field lines between two magnets or charges.
- I can explain how stored energy changes as objects move.
- I can tell whether energy is stored or released in an interaction.
HS-PS3-5 Worked Example
A floating magnet on a dowel makes the energy in a field easy to feel.
Where is the energy stored when one magnet floats above another?
Set It Up: Two ring magnets, a wooden dowel standing upright in a lump of clay, and a ruler.
- Slide both magnets onto the dowel with like poles facing.Top magnet floats about 2 cm up
- Press the top magnet down toward the lower one.The push gets harder the closer it gets
- Let go.It springs up past its resting height, then settles
- Flip the top magnet so opposite poles face, then pull the pair away from each other.They snap together, and separating them takes effort
- Draw field lines and an energy bar chart for each case.Like poles closer: more stored. Opposite poles closer: less
Pressing like poles together stored energy that came back as motion on release, while opposite poles gave up stored energy as they snapped together.
Why it works: The magnets act on each other through their shared field, and the energy stored in that field depends on their distance and which poles face each other.
Common Mistakes with HS-PS3-5
Thinking a force needs contact
“Nothing is touching the top magnet, so nothing holds it up.”
Try this: The magnets push through their field without touching. Drawing field lines between them shows where that force acts.
Mixing up the energy direction
“Opposite poles snapping together store more energy.”
Try this: Attracting objects lose stored energy as they come together, like a ball falling. Repelling objects gain stored energy when pushed closer.
Showing the force on one object only
An arrow on the top magnet but none on the bottom one
Try this: Draw an equal and opposite force arrow on each object, because both feel the interaction at the same time.
Where HS-PS3-5 Fits
Practice HS-PS3-5
Quick Check
- Two like charges are pushed closer together. Does the stored energy go up or down?
- Why do opposite charges speed up as they move toward each other?
- Magnet A pushes magnet B with 2 N. How hard does B push A?