Final answer:
Newton's third law states that every action has an equal and opposite reaction, which is what prevents Bernice from falling through the chair due to the normal force exerted by the chair. This principle is also illustrated by walking, driving, and swimming actions where forces are exerted and equal and opposite reaction forces are experienced.
Step-by-step explanation:
Newton's third law of motion states that for every action, there is an equal and opposite reaction. This law explains why a person, such as Bernice, does not fall through the chair they are sitting on. When Bernice sits on the chair, her body exerts a downward force on the chair due to gravity. In response, the chair exerts an upward force of equal magnitude on Bernice, which is the normal force. This normal force prevents her from falling through the chair.
In addition to this, examples of Newton's third law can be seen in everyday life. When a professor walks, they push backward on the floor, and the floor pushes forward on them, causing acceleration. A car accelerates when the ground pushes forward on the drive wheels in response to the wheels pushing backward. Similarly, a swimmer pushes against the pool wall, and in turn, is pushed forward by the wall.