Linear Momentum CalculatorFree online other calculator — instant results, no sign-up
Calculate momentum magnitude from mass and speed.
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About the Linear Momentum Calculator
The Linear Momentum Calculator finds an object's momentum magnitude by multiplying its mass in kilograms by its speed in meters per second. With the default mass of 10 kg and speed of 5 m/s, it returns 50 kg·m/s. This tool calculates magnitude only, not the direction of momentum.
- Mass (kg)
- The object's mass in kilograms (kg), with a default value of 10 kg.
- Speed (m/s)
- The object's speed in meters per second (m/s), with a default value of 5 m/s.
Formula and method
p = m × v; with the default inputs, p = 10 kg × 5 m/s = 50 kg·m/s.
- pLinear momentum magnitude, measured in kilogram-meters per second (kg·m/s).
- mThe object's mass, measured in kilograms (kg).
- vThe object's speed, measured in meters per second (m/s).
Use nonnegative mass and speed values expressed in the required units, then multiply mass by speed. The product is the classical linear momentum magnitude in kg·m/s; no direction is inferred.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Mass10 kg
- Speed5 m/s
Results
- Result50 kg·m/s
How to use the Linear Momentum Calculator
- 1Enter the object's mass in the Mass (kg) field; the default is 10.
- 2Enter its speed in the Speed (m/s) field; the default is 5.
- 3Check that the values are nonnegative and convert any measurements in other units to kg and m/s.
- 4Calculate momentum by multiplying mass by speed.
- 5Read the result in kg·m/s: the default inputs give 10 × 5 = 50 kg·m/s.
Reading your result
The Result row shows the object's linear momentum magnitude in kg·m/s. For the default inputs, 50 kg·m/s is the momentum magnitude of a 10 kg object moving at 5 m/s. A larger value means greater momentum magnitude, not necessarily greater kinetic energy or impact force. The output does not indicate a direction.
Limitations
This calculator uses classical mechanics, which is appropriate for speeds much lower than the speed of light; relativistic speeds require a different formula. Mass and speed must be nonnegative and use the stated units. Speed must be measured relative to a chosen reference frame, so the momentum depends on that frame. For an extended object, use its total mass and center-of-mass speed. The tool does not calculate vector components, kinetic energy, collision forces, or the net momentum of multiple objects.
Common questions
Why do the default inputs give 50 kg·m/s?+
Momentum magnitude equals mass multiplied by speed: 10 kg × 5 m/s = 50 kg·m/s.
Can I enter a negative speed to represent motion in the opposite direction?+
No. Speed is a nonnegative magnitude. Use the absolute value of a signed velocity for this calculator; calculating signed momentum or vector components requires direction information.
What happens to momentum if mass or speed doubles?+
Because p = m × v, doubling either mass or speed while holding the other fixed doubles momentum magnitude. Doubling both makes it four times as large.
Can the momentum result tell me the force of a collision?+
Not by itself. Average net force depends on the change in momentum divided by the time over which that change occurs. You would also need the final momentum, the relevant directions, and the collision duration.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.