Math
Momentum Calculator
Solve linear momentum p = m x v for momentum, mass, or velocity. Results in kg m/s, slug ft/s, km/h, mph, g, and lb.
Momentum Calculator
Given mass and velocity, compute p = m x v.
Mass of the moving object in kilograms. Must be greater than zero.
Velocity in meters per second. Sign denotes direction (negative means opposite direction).
Momentum
50 kg m/s
Momentum (kg m/s)
50 kg m/s
Momentum (slug ft/s)
11.240445 slug ft/s
Velocity (km/h)
18 km/h
Velocity (mph)
11.184681 mph
Mass (g)
10,000 g
Mass (lb)
22.046226 lb
Frequently Asked Questions about the Momentum Calculator
What is the formula for momentum?
Linear momentum is p = m x v, where m is mass in kilograms and v is velocity in meters per second. The result is in kg m/s. Momentum is a vector, so it carries the sign of the velocity.
Can momentum be negative?
Yes. Mass is always positive, but velocity can be negative when you pick a direction as your reference. A negative velocity means the object is moving the opposite way, so momentum will also be negative.
What is the difference between momentum and kinetic energy?
Momentum p = m x v is a vector that depends linearly on velocity, so direction matters and reversing the velocity flips the sign. Kinetic energy KE = 0.5 m v^2 is a scalar that depends on velocity squared, so direction does not matter.
How do I convert kg m/s to slug ft/s?
Multiply kg m/s by about 0.2248 to get slug ft/s. The calculator displays both units automatically and preserves the sign of momentum across both.
Why does the calculator reject some momentum and velocity combinations?
When you solve for mass, the calculator divides momentum by velocity. If the two have opposite signs (for example +100 kg m/s and -10 m/s), the math gives a negative mass, which has no physical meaning. The same happens at velocity equals zero.