Momentum Calculator — p = mv
Momentum measures how much motion an object carries: p = mv, mass times velocity. Enter any two values and the calculator finds the third.
Momentum is a vector — direction matters. In collisions, the total momentum before equals the total after (when no external impulse acts), which makes p = mv the starting point of almost every collision problem.
Use the calculator
Enter any TWO values — the calculator solves the third.
The formula
p = mv — so m = p/v and v = p/m. Momentum is measured in kg·m/s, equivalent to N·s.
Worked example
Worked example: A 0.5 kg ball moving at 12 m/s has momentum p = 0.5 × 12 = 6 kg·m/s. A 60 kg sprinter at 10 m/s carries 600 kg·m/s — one hundred times more.
Frequently asked questions
Is momentum a scalar or a vector?
A vector. It has the direction of the velocity, so in collision problems you must pick a positive direction and give momenta in the opposite direction negative values.
What is the difference between momentum and kinetic energy?
Momentum is p = mv (a vector, proportional to v), while kinetic energy is ½mv² (a scalar, proportional to v²). Collisions conserve momentum always; they conserve kinetic energy only when elastic.
What is impulse in terms of momentum?
Impulse equals the change in momentum: J = FΔt = Δp. It is why crumple zones and bending your knees when landing reduce force — the same Δp spread over a longer time.