Final answer:
The ball exerts an equal and opposite force on the baseball player, which is also 8.4 N but directed westward, according to Newton's third law.
Step-by-step explanation:
When a baseball player throws a ball, they exert a force on the ball. By Newton's third law, the ball exerts an equal and opposite force on the baseball player. So, when the baseball player throws a 151 g baseball directly eastward with a force of 8.4 N, the force that the ball exerts on the player is also 8.4 N, but it is directed westward, which is the opposite direction.
This situation is an example of action and reaction forces, which are present in all interactions and central to Newton's third law of motion. When you consider various sporting situations such as a basketball player jumping or an archer shooting an arrow, analyzing the forces and resulting motions gives you valuable insights into the physics of sports.