Question

what are differences between normal and normal force​

Answer 1

Answer:

• Force refers to its physical content - a response to the action of an object.
• Normal force refers to its direction - it is perpendicular to the surface

Explanation:

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Answer 2

The reaction force meantioned by Newton in his third law is not at all the same as the normal force.

Consider a pen laying on a table. Gravity pushes the pen down: it is the earth that exerts a force on the pen (gravity). The reaction force mentioned in the Third Law is the force the pen exerts on the earth, which is equal in magnitude but opposite to the original force the earth exerts on the pen. (Pen attracts Earth as much as Earth attracts Pen)

The normal force is the force exerted by the table on the pen, which keeps the pen from falling ‘through’ the table. The reaction force of the normal force is the force exerted by the pen on the table, which is only equal to the gravitational force on the pen if the table surface is perpendicular to the gravitational force vector.

If the pen would be laying on a slope, the normal force (which is always perpendicular to the surface) would not be equal to the gravitational force exerted on the pen:

Like you see in the above picture:

• Gravitational force is not perpendicular to the normal force (mg)
• The normal force has equal magnitude as the component of the gravitational force in the same direction. (N=mgcosθ)
• f is the friction force, needed for the object to be at rest. Without it, the object would slide off the slope. (f=mgsinθ)

To summarize:

• The normal force is a force perpendicular to the surface on which the object is laying. It is what keeps the object from falling through the surface.
• The reaction force of gravitational force is the force an object exerts on EARTH. Not on the surface it is laying!
• The reaction force of the normal force is the force the object exerts on the surface it is laying upon.
• The normal force IS NOT the reaction force of gravitational force, it is only equal in magnitude in a few situations!

I hope it helps you mate ✨