Enter any two of mass, velocity, or momentum and the Momentum Calculator solves for the third using the formula p = mv. Choose your calculation type, pick your preferred units for mass, velocity, and momentum, and get the result with a clear breakdown of the equation.
Result
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Result in SI Units (kg·m/s)
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Formula Applied
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Momentum (kg·m/s)
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Mass (kg)
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Velocity (m/s)
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Momentum (p) is a measure of how hard an object is moving — it depends on both its mass and its velocity. It is calculated using the formula p = mv, where m is the mass in kilograms and v is the velocity in meters per second. The SI unit of momentum is kg·m/s, which is equivalent to N·s.
Select which quantity you want to solve for — momentum, mass, or velocity. Then enter the two known values along with their units. The calculator will automatically convert your inputs to SI units, apply the correct form of p = mv, and display the result in your chosen unit system.
The calculator supports mass in kg, g, lb, and oz; velocity in m/s, cm/s, ft/s, in/s, and mi/h; and momentum in kg·m/s, N·s, g·cm/s, and lb·ft/s. All inputs are converted internally to SI before calculation, then converted back to your selected output unit.
Momentum (p = mv) is the quantity of motion an object has at any given instant. Impulse (J = F·Δt) is the change in momentum caused by a force acting over a time interval. Numerically, impulse equals the change in momentum, so they share the same SI unit: kg·m/s or N·s.
Momentum is a vector quantity — it has both magnitude and direction. The direction of momentum is the same as the direction of the object's velocity. In one-dimensional problems, direction is indicated by positive or negative signs, while in two or three dimensions, vector components are used.
The law of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act on it. This principle is central to analyzing collisions: in both elastic and inelastic collisions, the total momentum before equals the total momentum after the event.
Because momentum is directly proportional to mass (p = mv), a heavier object moving at the same velocity as a lighter one will have greater momentum. This is why a truck moving at 60 km/h is much harder to stop than a bicycle at the same speed — the truck has far more mass and therefore far more momentum.
Momentum appears in everyday scenarios: a bowling ball rolling down a lane, a car braking before a stop sign, a bullet fired from a gun, and a rocket expelling exhaust gases all involve momentum transfer. In sports, the momentum of a moving ball or player determines how difficult they are to stop or redirect.