Movement Amount

If we observe a game of pool, we will see that a ball transfers its movement totally or partially to another.

The physical magnitude that makes it possible to study these motion transfers is the amount of linear motion. , also known as momentum or linear momentum.

The amount of movement relates the mass of a body to its speed:

As characteristics of the amount of movement we have:

  • Module:
  • Direction: Same as speed.
  • Direction: Same as speed.
  • SI unit: kg.m / s.


How much movement of a 2kg mass body at a speed of 1m / s?

Impulse theorem

Considering Newton's 2nd Law:

And using it in the range of interaction time:

but we know that: , soon:

As we have seen:


"The momentum of a force, because of its application over a certain period of time, is equal to the variation in the amount of body movement that occurred within that same period of time."


How long should a force of intensity 100N act on a body of mass equal to 20kg, so that its speed goes from 5m / s to 15m / s?