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Collision Lab

Learning goal

Watch momentum survive every collision while kinetic energy survives only elastic ones — the green momentum bar never moves at impact; the yellow energy bar drops by exactly the amount turned to heat.

Things to try

  1. Equal masses, elastic (e = 1), target at rest: the balls swap velocities — Newton's cradle in slow motion.
  2. Slide e → 0 (perfectly inelastic): they stick and move at the center-of-mass velocity; note the KE loss — maximum allowed by momentum conservation.
  3. Heavy projectile, light target: the light ball leaves at nearly twice the projectile speed. Reverse the masses: the projectile bounces back.
  4. Head-on (\(v_2 < 0\)): total momentum can be zero while kinetic energy is large — vectors cancel, scalars don't.

Collisions & impulse · Linear momentum · Conservation of energy