Physics

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Momentum Calculator.

Calculate classical linear momentum from mass and signed velocity.

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Momentum: 10 kg·m/s

Momentum

0.000000kg·m/s

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Use Cases

Physics homework and exam prep

Quickly verify momentum calculations for problems involving moving objects, collisions, or impulse. Enter mass and velocity to check your work.

Example: A 5 kg object moving at 3 m/s has momentum 15 kg·m/s.

Engineering and design calculations

Estimate the momentum of moving parts or vehicles to assess impact forces or braking requirements. Useful for preliminary design checks.

Example: A 1200 kg car at 20 m/s has momentum 24000 kg·m/s.

Frequently Asked Questions

What is momentum and how is it calculated?
Momentum is the product of an object's mass and its velocity. In classical mechanics, it is calculated as p = m × v, where m is mass in kilograms and v is velocity in meters per second. The result is expressed in kg·m/s.
Why does the velocity have a sign?
Velocity is a vector quantity, meaning it has both magnitude and direction. The sign indicates direction along a chosen axis. A positive velocity points in the positive direction, while a negative velocity points opposite. This affects the sign of the momentum, reflecting the direction of motion.
Can momentum be negative?
Yes, momentum can be negative if the velocity is negative, since mass is always positive. A negative momentum simply means the object is moving in the negative direction relative to the chosen coordinate system.

Tips & Common Mistakes

Tips

  • Ensure mass is in kilograms and velocity in meters per second to get momentum in kg·m/s.
  • Remember that velocity is signed; use a negative value for motion in the opposite direction.
  • For a quick check, momentum magnitude equals mass times speed when direction is ignored.
  • Use the result to compare momenta of different objects; larger momentum indicates greater impact potential.

Common Mistakes to Avoid

  • Forgetting to include the sign of velocity, which changes the direction of momentum.
  • Using grams or other mass units without converting to kilograms.
  • Confusing momentum with kinetic energy; momentum is a vector, while kinetic energy is a scalar.

Last updated: August 13, 2026