Force is a vector
The result you get from applying a force changes according to its direction.
Figure to be added
Consider a loaded cart being pulled along by a bullock.
| Direction the force is applied | What happens to the cart |
|---|---|
| The direction it is moving | Its velocity increases |
| Opposite to the way it is moving | Its velocity decreases |
The magnitude of the force can be identical, yet the result is completely different depending on direction.
Force is a vector quantity
A force has a direction as well as a magnitude. That makes it a vector quantity — like displacement, velocity and acceleration.
Which is why "a force of 10 N" is only half a description. "A force of 10 N due east" is the whole of it.
The line of action
The direction in which a force acts at a point can be shown by a straight line drawn from that point. That line is called the force's line of action.
From here on
What we experience about force and motion was studied deeply by the scientist Sir Isaac Newton, who set out three laws. The next three sections take them one at a time.