The Normal Force
When a box rests on a horizontal surface, the Earth exerts a downward gravitational force on it (its weight).
However, the surface exerts an upward supporting force on the box, resulting in a net force of zero in accordance with Newton's First Law. This supporting force is called the normal force (often referred to as the surface reaction force).
[IMPORTANT: this is NOT an example of Newton's third Law, which is about an forces applied mutually on two objects (in this case the box and the surface)
In the case above we have TWO forces acting on the same box.]
But what if the surface is an incline, in other words, not perpendicular to the weight force?
The video examines the normal force and it's relationship to the incline. As yuou will see, its an application of Newton's Second Law
Interactive
Have a play with the following interactive. Ignore the friction for the moment (leave the coefficient to zero), until you have reviewed friction in the next lesson
Have a play with the following interactive. Ignore the friction for the moment (leave the coefficient to zero), until you have reviewed friction in the next lesson
Check out also this pHET interactive
At this stage this will only work on computers and not iPads
At this stage this will only work on computers and not iPads
Sample Problem
We are now ready to try a sample problem
Below is a sample problem with a video that explain how to solve it. It is suggested you try the problem beforehand, as this actually aids understanding, even if you are unsure if you are correct.
We are now ready to try a sample problem
Below is a sample problem with a video that explain how to solve it. It is suggested you try the problem beforehand, as this actually aids understanding, even if you are unsure if you are correct.
