Momentum
Momentum p = mv and its conservation: inelastic and elastic collisions, recoil and impulse.
What to find:
Velocities are projections on an axis: a body moving the other way has a negative velocity. Masses in kg, velocities in m/s (km/h ÷ 3.6). The mass is optional in the impulse mode.
The momentum calculator finds the momentum of a body, velocities after inelastic and elastic collisions, recoil velocity and impulse — using conservation of momentum.
Momentum and its conservation
p = mv; m1v1 + m2v2 = m1v1′ + m2v2′
In a closed system the total momentum does not change. Velocities are vectors, so a body moving the other way gets a minus sign.
| Collision | Velocity after |
|---|---|
| perfectly inelastic (bodies stick) | v = (m1v1 + m2v2) / (m1 + m2) |
| recoil (from rest) | v2 = −m1v1 / m2 |
Example. A 10 kg shell leaves a 2000 kg gun at 600 m/s: recoil velocity v = −10 · 600 / 2000 = −3 m/s.
The impulse of a force equals the change in momentum: FΔt = Δp.
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