The momentum calculator computes linear momentum using p = mv (mass × velocity). Solve for momentum, mass, or velocity. Supports metric (kg·m/s) and imperial (slug·ft/s) units — essential for collision physics, impulse calculations, and conservation of momentum problems.
Momentum Calculator (p = mv)
How to Use the Momentum Calculator
This momentum calculator solves for any variable in the linear momentum equation p = mv. Momentum is a vector quantity — it has both magnitude and direction — but this calculator handles the scalar magnitude.
Step 1: Choose What to Calculate
Select Momentum (p), Mass (m), or Velocity (v) to solve for. The selected field is grayed out and calculated from the other two.
Step 2: Select Units
Metric uses kg·m/s for momentum. Imperial uses slug·ft/s. A slug equals 14.594 kg.
Conservation of Momentum
In a collision, total momentum is conserved if no external forces act. If a 1000 kg car moving at 15 m/s strikes a stationary 800 kg car and they stick together: p_before = 1000 × 15 = 15,000 kg·m/s, and combined velocity = 15,000 / 1800 = 8.33 m/s.
Real-World Examples
Football tackle: A 100 kg player at 6 m/s has momentum = 600 kg·m/s. A 90 kg player must move faster than 6.67 m/s to match this momentum.
Rocket propulsion: Rocket engines work by ejecting mass at high velocity, giving the rocket equal and opposite momentum — conservation in action.
Frequently Asked Questions
What is momentum in physics?
Momentum (p) is the product of an object's mass and velocity: p = mv. It measures how hard it is to stop a moving object. A 1000 kg car moving at 20 m/s has momentum = 20,000 kg·m/s. Momentum is conserved in collisions when no external forces act — the total momentum before equals total momentum after.
What is the difference between momentum and kinetic energy?
Momentum p = mv is proportional to velocity, while kinetic energy KE = ½mv² is proportional to velocity squared. Doubling speed doubles momentum but quadruples kinetic energy. Momentum is a vector (has direction) while kinetic energy is a scalar.
Is this calculator free?
Yes, completely free with no signup required. All calculations run in your browser.
Is my data private?
Yes. All calculations run locally. Nothing is sent to any server.
What are slugs in imperial momentum units?
A slug is the imperial unit of mass. 1 slug = 14.5939 kg. Momentum in imperial is measured in slug·ft/s. A 1 slug object moving at 10 ft/s has momentum = 10 slug·ft/s = 145.939 kg·m/s.