Final answer:
Jeremy's arm operates as a third-class lever while throwing a baseball, with the shoulder joint as the fulcrum, muscle force as the effort, and the baseball as the load, allowing for high-speed pitches.
Step-by-step explanation:
When Jeremy throws a baseball, his arm is operating as a third-class lever. In this type of lever, the fulcrum is at one end (the shoulder joint), the effort is applied between the fulcrum and the load (the muscle force is applied between the shoulder and the hand holding the ball), and the load (the baseball) is at the other end. In the case of pitching a baseball, the biceps apply the effort by contracting, the elbow acts as the fulcrum, and the ball itself is the load. Baseball bats, hammers, and golf clubs are examples of a third-class lever, where the effort force is applied close to the fulcrum, and they exert a large force to a short effort arm, which results in a smaller force acting over a greater distance at the end of the resistance arm. The nature of this lever allows for the high-speed release of the ball, as in fast pitches in softball where the ball can leave the hand at speeds up to 139 km/h.