Normal Force Definition:
* The normal force is the force exerted by a surface to prevent an object from passing through it. It's always perpendicular to the surface.
Weight Definition:
* Weight is the force of gravity acting on an object's mass. It's always directed towards the center of the Earth.
When They Are Opposite:
* Object at Rest on a Horizontal Surface: When an object is at rest on a horizontal surface, the normal force and weight are equal in magnitude and opposite in direction. This is because the surface is preventing the object from falling through it.
When They Are Not Opposite:
* Object on an Inclined Plane: When an object is on an inclined plane, the normal force is perpendicular to the plane, while the weight is still directed downwards. The normal force and weight are no longer opposite in direction.
* Object in Freefall: An object in freefall experiences only the force of gravity (weight). There is no surface for the normal force to act upon.
* Object on a Curved Surface: On a curved surface, the normal force is perpendicular to the surface, which may not be directly opposite the weight.
Key Point:
The normal force is always perpendicular to the surface, while the weight is always directed towards the center of the Earth. They are only opposite when the surface is horizontal and the object is at rest.
