Enter the mass and velocity of an object to calculate the linear momentum of that object in one dimension. Momentum is a vector quantity, meaning it has magnitude and direction. In this case, the calculator assumes the object is moving in only one direction.

Momentum Formula

Momentum is the product of mass and velocity.

Momentum(p) = mass (m) * velocity (v)

Velocity is a vector quantity, meaning it has direction. As a result, the momentum of an object is also a vector quantity because it’s the product of velocity and mass.

Momentum is measure in kilogram meters per second (kg*m/s) in SI units. The rate of change of momentum in a closed system is equal to the net force acting on that object. That means the force is equal to the derivative of momentum with respect to time.

In a closed system, the total momentum is constant. For example, let’s imagine a close system of two-point objects. If object one increases its momentum by 5 kg*m/s, then object two must have had its momentum decreased by the same amount in the opposite direction.

Because momentum is a measurable quantity, the reference frame of that measurement affects the outcome. For example, if someone is moving in a car, with respect to that care they have no velocity and no momentum, but you move the reference frame to someone observing from the street, that person has a velocity and therefore a momentum.

How to calculate momentum

To calculate momentum, you need to know both the mass and velocity of an object. To calculate the mass of an object, you can either use empirical methods like a scale or use the formula for mass. Mass is equal to the density times the volume.

Let’s take a look at a common problem given in physics and calculate the momentum of an object.

  1. First, we need to measure the weight of the object. For simple calculations, this can be done accurately enough using a scale. Let’s say we measure 25 kg.
  2. Next, we need to measure or calculate the velocity. Sometimes velocity is provided as a number and other times it needs to be calculated through position and time. For this example, we will just assume a velocity of 10 m/s.
  3. Finally, enter the information into the formula or calculator above. M = 25 kg * 10m/s = 250 kg*m/s.
  4. Analyze the results and apply them to additional problems.

Momentum Definition

Momentum is defined as the product of the mass and velocity of an object.