About the Coefficient of Restitution
The coefficient of restitution measures how lively a collision feels. It compares the speed after impact with the speed before impact. A value near zero means the objects stick or rebound weakly. A value near one means the rebound keeps most relative motion. Values above one can appear when stored energy is released during impact.
Why This Calculator Helps
This calculator supports two common test styles. The velocity method works well for carts, balls, and moving objects. Enter each object's velocity before and after impact. The height method works for bounce tests. Enter the drop height and rebound height. The tool then reports restitution, energy retention, energy loss, and a simple collision class.
Practical Measurement Tips
Use the same direction sign for every velocity. A rightward velocity can be positive. A leftward velocity can be negative. This keeps the relative speed correct. For bounce tests, measure height from the same reference point. Use meters, feet, or centimeters consistently. Repeat the test several times. Average results reduce random error.
Interpreting Results
A perfectly inelastic collision has a coefficient of zero. The bodies have no separation speed after impact. A partially elastic collision has a value between zero and one. Most real sports balls and materials fall here. An elastic collision has a value near one. Superelastic results need review. They may mean extra energy entered the system. They may also reveal measurement mistakes.
Energy and Momentum Notes
Restitution is not the same as energy efficiency. It is based on relative speed. Energy depends on mass and velocity squared. That is why this calculator also accepts optional masses. When masses are entered, it estimates kinetic energy before and after impact. It also reports momentum change for each object. These values help compare materials, surfaces, and test conditions.
Best Use Cases
Use it for classroom experiments, lab reports, product checks, and coaching analysis. It can compare rubber balls, steel balls, carts, packaging drops, and rebound surfaces. Keep inputs realistic. Clean the test surface. Record temperature when materials are sensitive. Review the warning messages when the approach speed is too small, because tiny speed differences can create unstable answers. Save each result to document your testing process later clearly.