Inelastic Collision Calculator
Find the common final velocity when two objects collide and stick together in a perfectly inelastic collision.
How it works
- 1Enter the mass and initial velocity of each object before the collision.
- 2The calculator applies conservation of momentum: v = (m₁u₁ + m₂u₂) ÷ (m₁ + m₂) to find the shared velocity.
- 3Results update instantly in your unit system; the total momentum is shown to confirm it is conserved.
Use cases
- Physics students solving perfectly inelastic collision problems.
- Engineers analysing low-speed impacts where objects crumple and move together, like crash tests.
- Teachers demonstrating momentum conservation and kinetic energy loss.
Frequently asked questions
What is a perfectly inelastic collision?
One in which the objects stick together and move as a single mass afterwards. It gives the maximum kinetic-energy loss while still conserving momentum. The common velocity is v = (m₁u₁ + m₂u₂) ÷ (m₁ + m₂).
Why is kinetic energy not conserved?
The objects deform, generate heat, and make sound — irreversible processes that convert kinetic energy to other forms. So the kinetic energy after is always less than before, while momentum stays conserved.
Can you walk through a worked example?
A 2 kg object at 3 m/s strikes a stationary 1 kg object and they stick. Total momentum = 6 kg·m/s, combined mass = 3 kg, final velocity = 2 m/s. KE before = 9 J, after = ½ × 3 × 2² = 6 J — 3 J became heat and deformation.
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