Physics

Momentum and Impulse Calculator

Enter mass and velocity, and optionally a force and the time it acts.

By TheCalcTools Updated October 17, 2026 Formula checked and tested

Your numbers

Mass

Velocity

Force applied

Time the force acts (s)

Momentum (kg·m/s)

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Impulse (N·s)

—

Velocity after the impulse (m/s)

—

Kinetic energy before (J)

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Momentum is mass times velocity. An impulse, force × time, changes momentum by exactly that amount (Newton’s second law in impulse form).

Airbags and crumple zones work by stretching the time of a collision so the same change in momentum needs a smaller force.

p = mv; J = FΔt = Δp

Using the default values shown in the calculator:

A 1,200 kg car at 25 m/s has momentum 30,000.00 kg·m/s.
Braking with 6,000 N for 2 s gives an impulse of -12,000.00 N·s, leaving 15.00 m/s.

Result:

Momentum (kg·m/s)	30,000.00
Impulse (N·s)	-12,000.00
Velocity after the impulse (m/s)	15.00
Kinetic energy before (J)	375,000

Is momentum conserved?

In any collision with no outside force, total momentum before equals total momentum after.