Elastic Collision Calculator
Both limiting cases, with the energy lost in each.
Work out Elastic Collision. Both limiting cases, with the energy lost in each. Names the assumption that breaks it.
Negative if it moves towards object 1.
Velocities after an elastic collision
0 and 5 m/s
Perfectly inelastic they would both move at 2.5 m/s
Momentum is conserved in every collision without exception. Kinetic energy is conserved only in a perfectly elastic one, and a perfectly inelastic collision — where the bodies stick together — loses the most energy possible while still conserving momentum. Real collisions sit somewhere between. Watch the equal-mass elastic case: the velocities simply swap. That is why a Newton's cradle passes the motion straight through the middle balls, and why a head-on cue ball stops dead.
How the Elastic Collision Calculator works
Enter two masses and velocities for the outcome of both a perfectly elastic and a perfectly inelastic collision, along with the kinetic energy in each case. Momentum is conserved in both; energy only in the elastic one.
Also known as: inelastic collision calculator · collision velocity calculator · conservation of momentum calculator · 1d collision calculator
Frequently asked questions
What is conserved in a collision?
Momentum, always, in every collision without exception. Kinetic energy is conserved only in a perfectly elastic one.
What happens when equal masses collide elastically?
The velocities swap exactly. That is why a Newton's cradle passes motion straight through the middle spheres, and why a square-on cue ball stops dead.
What is a perfectly inelastic collision?
One where the objects stick together and move as a single body. It loses the maximum energy possible while still conserving momentum, which is the most any collision can lose.
Are real collisions elastic or inelastic?
Somewhere between. Steel balls come close to elastic, a car crash close to inelastic. The coefficient of restitution measures where on that scale a real collision sits.
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