Inelastic Collision Calculator

An inelastic collision is one where kinetic energy is not conserved — some energy is converted into heat, sound, or deformation. Momentum is still conserved in all collision types (elastic and inelastic), but the total kinetic energy decreases after an inelastic collision. See also our kg to Newtons Calculator.

In a perfectly inelastic collision, the two objects stick together and move as one combined mass after impact — this results in the maximum possible kinetic energy loss. In a partially inelastic collision, the objects separate after impact but with reduced relative velocity, quantified by the coefficient of restitution (e), which lies between 0 and 1.

The coefficient of restitution (e) is a value between 0 and 1 that describes how much relative velocity is retained after a collision. A value of 0 means perfectly inelastic (objects stick together), while a value of 1 means perfectly elastic (no energy loss). Values in between represent partially inelastic collisions.

Yes. Momentum is always conserved in all types of collisions — elastic, perfectly inelastic, and partially inelastic — as long as no external forces act on the system. The law of conservation of momentum states that the total momentum before the collision equals the total momentum after. You might also find our calculate Newton's Third Law useful.

For a perfectly inelastic collision, both objects merge and move together. The final velocity is calculated as: v = (m₁·u₁ + m₂·u₂) / (m₁ + m₂), where m₁ and m₂ are the masses and u₁ and u₂ are the initial velocities of the two objects.

The kinetic energy lost in an inelastic collision is converted into other forms of energy, such as heat, sound, light, or energy used to deform the objects. For example, when two cars collide and crumple, the energy goes into bending the metal and generating heat.

Yes. Negative velocity values represent motion in the opposite direction. For example, if Object 1 moves to the right at +10 m/s and Object 2 moves to the left at -5 m/s, entering these signed values will correctly account for the opposing directions in the momentum calculation.

A classic example is two train cars coupling together — after the collision, they move as one unit. Other examples include a ball of clay hitting a surface and sticking, or a football tackle where a defender grabs a ball carrier and they move together momentarily.