Calculate impulse, change in velocity, and average force from mass and velocity change using the impulse-momentum theorem. Free online physics calculator.
An impulse calculator lets you instantly compute the impulse delivered to an object — and, if you provide a time interval, the average force involved — using the impulse-momentum theorem. Enter an object's mass, its initial and final velocity, and (optionally) the time over which that velocity change occurred, and the calculator returns the impulse (J = mΔv) and average force (F = J/Δt).
Impulse describes the cumulative effect of a force acting over time, and it's mathematically identical to the change in momentum an object experiences. This equivalence — the impulse-momentum theorem — is one of the most practically useful ideas in classical mechanics, because it explains why the same change in velocity can feel wildly different depending on how quickly it happens: a car crashing into a wall at 50 km/h stopping in 0.1 seconds produces a vastly larger force than the same car decelerating to a stop over 5 seconds using its brakes, even though the momentum change is identical.
This calculator is useful in many contexts: physics students use it to solve collision and momentum-change problems, safety engineers use it to understand how airbags, crumple zones, and padding reduce injury by extending impact time, and sports scientists and coaches use it to analyze techniques like following through on a swing or 'giving' with an impact to control force.
A baseball with a mass of 0.145 kg is hit by a bat, changing its velocity from 0 m/s to 40 m/s in about 0.7 milliseconds (0.0007 s). The impulse is J = 0.145 × (40 - 0) = 5.8 N·s. The average force the bat exerts on the ball during contact is F = 5.8 / 0.0007 ≈ 8,286 N — a huge force, but only briefly applied.
The impulse value this calculator produces represents the total 'push' delivered to change the object's momentum — a larger magnitude means a bigger change in motion, whether from a stronger force, a longer duration, or both. When you also provide a time interval, the average force tells you how intense that push was moment-to-moment. Notice in the reference table how vastly different scenarios — a gentle tennis serve versus a rocket launch — span many orders of magnitude in impulse, even though the underlying physics (J = mΔv) is identical. If your calculated average force seems surprisingly large, check your time interval — real-world collisions often happen in milliseconds, and even a modest momentum change divided by a tiny Δt produces a very large force, which is exactly why short, sudden impacts are so much more damaging than the same momentum change spread over a longer time.
Enter the object's mass, its initial and final velocity, and the time interval over which the velocity changed — the calculator computes impulse using J = mΔv, and the average force using F = J/Δt.
| Scenario | Impulse |
|---|---|
| Tennis ball struck by a serve | 3 N·s |
| Baseball hit by a bat | 6 N·s |
| Boxing punch to a heavy bag | 15 N·s |
| Car colliding with a wall at moderate speed | 8,000 N·s |
| Rocket engine impulse at launch | 5,000,000 N·s |