Define normal force. What is its relationship to friction

Solution 1CQ :

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        In physics we often use the word called normal force.

        This is the normal reaction from a surface or some short of thing which an object gets.

        Imagine you are standing on an elevator which is not moving.

        By the principle of gravity, earth exerts a force  on you towards it.

        By the Newton’s 3rd law, the floor also must exert a force on you by the same amount but in an opposite direction.

        This force is called the normal reaction.