Q19CQ - College Physics (Urone)

Question

An American football lineman reasons that it is senseless to try to out-push the opposing player, since no matter how hard he pushes he will experience an equal and opposite force from the other player. Use Newton’s laws and draw a free-body diagram of an appropriate system to explain how he can still out-push the opposition if he is strong enough.

Step-by-Step Solution

Answer

If the lineman exerts more force on the opposing player, he could out-push the opponent.

Step 1: Newton’s third law.

Newton’s third law states that for every action, there is an equal and opposite reaction. If a body exerts a force on another body, an equal force that will be directed in the opposite direction will be exerted on the body by another body.

The free body diagram of a system can be drawn by including all the forces that act on the system.

Step 2: Draw the free body diagram and show how the resultant force is generated.

The free body diagram of a football player is shown below.

Here, F is the force exerted by the player, f is the force of friction, W is gravitational force and N is the normal force acting perpendicular to the surface. The same kind of external forces acting on the opposing player will also exert a resultant net force on the lineman. Since the two forces are acting on different bodies, they won’t cancel. So, if the lineman exerts more force, he can push out the opposing player.

Therefore, it is possible for the lineman to push the opposing player by exerting more force.