Forces and Vectors

In order for the inertia of an object to change an outside force must be applied to that object.

A force is any push or pull.

Forces are constantly being applied to objects. The sum of all these forces is the net force and if the net force equals zero the object is in equilibrium.

 F = net force

If the object is moving it is in dynamic equilibrium and if the object is at rest it is in static equilibrium.

Forces are measured in newtons. A newton is one kilogram meter per second per second. (1 kg · m/s2)


Forces are also vector quantities. A vector has both direction and magnitude.
A scalar has only magnitude.


  • 30 miles per hour is a scalar 
  • 30 miles per hour north is a vector


Since physics deals with vectors you need to understand how physics deals with direction. Direction is put into terms of negative and positive combined with angles.

  • Up or North is positive 
  • Down or South is negative 
  • Right or East is positive 
  • Left or West is negative