Momentum Calculator

Find the momentum and kinetic energy of a moving mass.

Inputs

kg
m/s
Formulas
p = m·v
KE = ½·m·v²

Results

Momentum kg·m/s
Kinetic energy J

What is momentum?

Momentum is the product of an object's mass and velocity, p = mv. It is a vector, pointing in the direction of motion, and measures how hard it is to stop a moving object. A slow-moving truck and a fast bullet can carry similar momentum despite very different masses and speeds.

p = m·v

Conservation of momentum

In any isolated system, the total momentum is conserved: it stays constant unless an external force acts. This principle governs collisions, explosions, and rocket propulsion. This calculator returns both the momentum and the kinetic energy, ½mv², so you can compare the two ways of describing a moving object.

Frequently asked questions

Is momentum always conserved?

Total momentum is conserved whenever no net external force acts on the system. Internal forces between colliding objects cancel out.

How is momentum different from kinetic energy?

Momentum is a vector that scales with velocity; kinetic energy is a scalar that scales with velocity squared. Both are conserved in elastic collisions, but only momentum is conserved in inelastic ones.

Read the full guide