Momentum Calculator
Enter any two of momentum, mass, and velocity, and it returns the third from p = m·v.
Fill in any two fields and leave the third blank — the calculator solves for the one you left empty using p = m·v.
Momentum
50kg·m/s
Mass
10kg
Velocity
5m/s
How it works
Momentum is mass times velocity — a measure of how much oomph a moving object carries. A 10 kg cart rolling at 5 m/s has 50 kg·m/s of momentum, and it takes exactly that much impulse to stop it.
Because the formula is a simple product, you can rearrange it to find whichever quantity you're missing. Divide momentum by velocity to recover the mass, or by mass to recover the velocity. Leave one field blank and the calculator handles the algebra.
Heavier objects and faster objects both carry more momentum, which is why a slow freight train and a fast bullet can be equally hard to stop. In a collision, the total momentum of everything involved stays constant — the principle behind everything from billiards to rocket launches.
Frequently asked questions
What are the units of momentum?
In SI units, mass in kilograms times velocity in meters per second gives momentum in kilogram-meters per second (kg·m/s). There's no separate named unit — it's just written out.
Is momentum the same as kinetic energy?
No. Momentum is m·v and points in a direction, while kinetic energy is ½·m·v² and has no direction. Double an object's speed and its momentum doubles but its kinetic energy quadruples.
Can momentum be negative?
Yes, if you treat one direction as positive. An object moving left with a leftward-negative convention has negative momentum. The sign just tracks direction along your chosen axis.