Normal Force Direction
When the surface's molecules push back on the body, they push straight
out from the surface. Thus, the force is always perpendicular to the
surface. In mathematics, "normal" is used as a synonym for
"perpendicular." Thus, the force is called the "normal" force.
For instance, if the surface is tilted, as shown below, then the normal force is tilted too. In fact, if the surface is tilted at 45 degrees, then the normal force direction is 45+90=135 degrees.
