Question

A plank is inclined at an angle (o) north of west. What is the direction of the normal force exerted by that plank on an object? The direction of the normal force would be oriented at angle (o) with respect to which direction?

1) North of west
2) South of west
3) East of west
4) West of north

Answer 1

The normal force on an inclined plane acts perpendicular to the surface, directed away from the plane. Since the plane is inclined north of west, the normal force would actually be oriented south of east, directly opposite to the perpendicular component of gravity on the plane.

Step-by-step explanation:

When considering the direction of the normal force on an inclined plane, it's important to remember that this force always acts perpendicular to the surface of contact. Since the plank is inclined 'north of west,' the direction of gravity is vertically downward resulting in a normal force that is perpendicular to the plane itself. This means the normal force would not be aligned north of west, but precisely opposite to the component of the gravitational force that acts perpendicular to the plane. Therefore, if the plank makes an angle o with the horizontal, the normal force would be oriented at angle o south of east if you are looking along the plane in the downward direction (which is in the opposite sense to 'north of west').

In other words, the normal force is directed away from the surface of the inclined plane, which is towards the southeast if looking down from the top of the plane along its length. Hence, the correct answer to the direction of the normal force is option 2) South of east, as it is perpendicular to the surface.