Track the signs
Rightward velocity is positive and leftward velocity is negative.
Collision Carts
Collide carts to compare signed momentum and kinetic energy before and after impact.
Grades 3–5 · Physics
Your goal
Collide a 1 kg cart A moving at +3 m/s with a 1 kg cart B at 0 m/s. Use an elastic collision and compare momentum before and after.
Reduced motion is on. The controls still update the scene.
Total momentum is 2.00 kg m/s before and 2.00 kg m/s now. Kinetic energy is 2.00 J before and 2.00 J now. Positive velocity points right.
kg
kg
m/s
m/s
The track is horizontal and frictionless. The scene compares moments before and after a one dimensional collision, with schematic cart positions. Elastic collisions conserve kinetic energy. Sticking collisions conserve momentum while transferring kinetic energy to other forms.
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Learn with Collision Carts
Collision Carts gives elementary students a concrete way to compare motion before and after impact. Set the mass and starting velocity of each cart, choose an elastic collision or a sticking collision, and bring the carts together. Arrows and signed velocity readings show whether each cart moves left or right. The total momentum display stays consistent across the collision, while kinetic energy reveals a difference between the two collision types. Students can test equal masses, unequal masses and opposing motion, then explain where kinetic energy goes when carts stick.
What to look for
Compare equal masses
Equal masses exchange velocities during an ideal elastic collision.
Watch a sticking pair
Sticking carts share a final velocity and lose some kinetic energy to other forms.
For teachers and curious learners
Test momentum conservation in elastic and sticking collisions with different masses. Ask students to predict what will happen, change one setting, and explain what they observe. Learn gives a starting point. Practice and Challenge offer new goals with the same scene.
One dimensional carts move on a frictionless horizontal track. Elastic collisions conserve kinetic energy; perfectly inelastic sticking collisions convert some kinetic energy to other forms while conserving momentum.