About this tool
The Momentum & Impulse Calculator is a free, in-browser mechanics tool with two modes. Momentum mode uses p = m·v to solve for momentum, mass or velocity; impulse mode uses J = F·Δt to solve for impulse, force or time, and — because the impulse–momentum theorem says J = Δp = m·Δv — it also reports the resulting change in velocity when a mass is given.
All quantities use SI units: mass in kilograms, velocity in metres per second, momentum in kg·m/s, force in newtons, time in seconds and impulse in newton-seconds (N·s), which are numerically identical to kg·m/s.
Calculations run entirely on your device with no uploads, updating live as you type so you can explore how force and contact time trade off to change an object's momentum.
Frequently asked questions
What units does the tool use?
Mass in kilograms, velocity in m/s, momentum in kg·m/s, force in newtons, time in seconds, and impulse in newton-seconds (N·s). Note 1 N·s equals 1 kg·m/s.
How are impulse and change in velocity related?
The impulse–momentum theorem states J = FΔt = Δp = mΔv. In impulse mode the tool computes J = F·Δt, then divides by the entered mass to show the resulting change in velocity Δv.
Can momentum or velocity be negative?
Yes. Momentum is a vector, so a negative velocity gives a negative momentum, indicating motion in the opposite direction along your chosen axis. Force may also be negative to represent an opposing push.
Why does Δv only appear sometimes?
The change-in-velocity tile is shown only when you enter a positive mass in impulse mode; without a mass the impulse itself is still reported in N·s.