Calculate final velocities for elastic and inelastic collisions between two objects
Enter masses and initial velocities for collision calculation
Enter parameters and calculate to see results
Momentum is conserved in all collisions. Kinetic energy is conserved only in elastic collisions.
Total momentum before collision equals total momentum after collision.
v1f = (m1 - m2)/(m1 + m2) * v1i + (2m2)/(m1 + m2) * v2i v2f = (2m1)/(m1 + m2) * v1i + (m2 - m1)/(m1 + m2) * v2i
vf = (m1 * v1i + m2 * v2i) / (m1 + m2)
Energy conserved
Energy lost
Objects stick together
Collisions are fundamental to understanding momentum and energy conservation in physics. Our Collision Calculator helps you compute the final velocities of two objects after elastic or inelastic collisions, providing insights into conservation laws and real-world applications.
A collision occurs when two objects interact briefly, exchanging momentum and possibly energy.
Elastic Collision: Both momentum and kinetic energy are conserved. No energy is lost to heat, sound, or deformation. Objects bounce off each other.
Inelastic Collision: Momentum is conserved, but kinetic energy is not. Some energy is converted to other forms like heat or sound. Objects may stick together in perfectly inelastic collisions.
Most real-world collisions are inelastic, while elastic collisions are ideal for atomic or subatomic interactions.
The formulas depend on the collision type and assume one-dimensional motion for simplicity.
Elastic Collision (1D): v₁f = ((m₁ - m₂) / (m₁ + m₂)) * v₁i + ((2m₂) / (m₁ + m₂)) * v₂i v₂f = ((2m₁) / (m₁ + m₂)) * v₁i + ((m₂ - m₁) / (m₁ + m₂)) * v₂i Inelastic Collision (1D): v_f = (m₁ * v₁i + m₂ * v₂i) / (m₁ + m₂) Perfectly Inelastic Collision: Objects stick together with velocity v_f above. Where: m₁, m₂ = masses of objects 1 and 2 v₁i, v₂i = initial velocities v₁f, v₂f = final velocities v_f = final velocity (combined)
Example 1: Elastic Collision - Equal Masses
Mass 1 = 1 kg, Velocity 1 = 5 m/s
Mass 2 = 1 kg, Velocity 2 = -3 m/s
v₁f = ((1-1)/(1+1))*5 + ((2*1)/(1+1))*(-3) = 0 + 1*(-3) = -3 m/s
v₂f = ((2*1)/(1+1))*5 + ((1-1)/(1+1))*(-3) = 1*5 + 0*(-3) = 5 m/s
👉 Velocities are exchanged: Object 1 ends at -3 m/s, Object 2 at 5 m/s.
Example 2: Inelastic Collision - Stationary Target
Mass 1 = 2 kg, Velocity 1 = 4 m/s
Mass 2 = 3 kg, Velocity 2 = 0 m/s
v_f = (2*4 + 3*0) / (2 + 3) = 8 / 5 = 1.6 m/s
👉 Combined velocity = 1.6 m/s
Q1. What's the difference between elastic and inelastic collisions?
Elastic collisions conserve both momentum and kinetic energy. Inelastic collisions conserve momentum but not kinetic energy.
Q2. Can objects stick together in a collision?
Yes, in perfectly inelastic collisions, objects stick together and move with a common final velocity.
Q3. Are real-world collisions elastic or inelastic?
Most real-world collisions are inelastic, with some energy lost to heat, sound, or deformation.
Q4. How does mass ratio affect collision outcomes?
In elastic collisions, lighter objects bounce back more, while heavier objects barely change velocity.
Q5. What is coefficient of restitution?
The coefficient of restitution (e) measures elasticity: e = 1 for perfectly elastic, e = 0 for perfectly inelastic.
For further understanding and validation of the formulas used above, we recommend exploring these authoritative resources: