Question

As you stand on a floor, the floor exerts an upward force on you. why are you not moved upward by this force? 1. the upward force is less than your weight, so you do not move up. 2. the upward force is greater than your weight, but air pressure pushes you down. without the air, you would be lifted up. 3. the upward force is equal to your weight and the two forces cancel each other. 4. none of these 5. the upward force is negligible

Answer 1

Newton's third law of motion states that for any action, there is equal and opposite force. For a person standing on a floor, the action force is the weight and thus the floor must exert an opposite and equal reaction force equivalent in magnitude to the weight of the person.

In this regard, statement 3. is correct.