Here's a breakdown:
* Normal in this context means "perpendicular".
* Force is a push or pull that can cause a change in motion.
* Surface of contact is the area where two objects touch.
Examples:
* A book resting on a table: The table exerts a normal force upward on the book, counteracting the force of gravity pulling the book downward.
* A person pushing a box against a wall: The wall exerts a normal force on the box, pushing it back.
Key points about normal force:
* It is always perpendicular to the surface of contact.
* It is a reaction force to the force exerted by the object on the surface.
* It can be zero if the object is not in contact with the surface.
* It can be calculated using Newton's third law of motion (for every action, there is an equal and opposite reaction).
Let me know if you have any further questions!
