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Mihsaba›Perfectly Inelastic Collision Calculator

Perfectly Inelastic Collision Calculator

Calculate the shared final velocity for a 1D perfectly inelastic collision, with momentum and kinetic-energy loss.

These are idealized models: collision assumes sticking, free fall ignores air drag, and the pendulum uses the small-angle approximation.

How to use

In a perfectly inelastic collision the bodies stick together, so linear momentum is conserved while kinetic energy generally is not. Signed velocities represent direction.

  1. Enter both masses.
  2. Enter signed velocities.
  3. Calculate shared velocity and energy before/after.

How it is calculated

vf=(m₁v₁+m₂v₂)/(m₁+m₂)

Example

Example: 2 kg at 4 m/s collides with 3 kg at −1 m/s and sticks; shared final velocity is 1 m/s.

Important notes

This is a 1D perfectly inelastic model. Elastic or 2D collisions require different equations.

Frequently asked questions

Why does kinetic energy fall?

Some becomes deformation, heat, sound and other forms.

Is momentum always conserved?

Approximately for an isolated system during the collision.

Why negative velocities?

To encode direction on one axis.