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Coefficient of Restitution from Pre/Post-Collision Velocities Calculator

e = (v_f2 − v_f1) / (v_i1 − v_i2).

Compute the dimensionless coefficient of restitution e (a measure of energy lost in a collision) from the pre- and post-collision velocities of two colliding objects. e = 1 for a perfectly elastic collision, e = 0 for a perfectly inelastic collision, and 0 < e < 1 for real (lossy) collisions.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

m/s
m/s
m/s
m/s

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

e = (v_f2 − v_f1) / (v_i1 − v_i2).

In depth

Compute the dimensionless coefficient of restitution e (a measure of energy lost in a collision) from the pre- and post-collision velocities of two colliding objects. e = 1 for a perfectly elastic collision, e = 0 for a perfectly inelastic collision, and 0 < e < 1 for real (lossy) collisions.