Question

Using all three of Newton's laws of motion, carefully describe the motion of a baseball beginning when the ball is resting in the pitcher's glove as he stands on the mound until the ball is hit by the batter (assume the ball is hit). Ignore what kind of pitch is thrown and air resistance. The answer should focus on the forces and motion of the ball (not the players), and should include which of Newton's laws each motion/force follows. в у = = т т. O Words

Answer 1

Answer:

As the ball sits in the glove of the pitcher, it is acted upon by the downward force of gravity. Based on Newton’s 3rd law (N3), the ball pulls upward on the Earth with exactly the same force. The force of gravity is perfectly balanced by the upward normal force of the glove on the ball. There is no net force, so the ball remains at rest in the glove based on Newton’s 1st law (N1). When ready to pitch, the pitcher’s hand lifts the ball out of the glove. The ball is now being acted on by a net force from the pitcher’s hand and experiences motion, per Newton’s 2nd law (N2). The upward force of the pitcher’s hand on the ball is stronger than the downward pull of gravity, so the ball moves up, out of the glove, and behind the pitcher’s head. Its inertia is continually changing due to the net force (N1). During this movement, the ball is exerting a force on the pitcher’s hand equal and opposite to the force the hand exerts on the ball (N2). Because the ball’s mass is smaller, its acceleration is larger, resulting in a net movement of the ball. As the pitcher throws the ball forward, he exerts a large force on the ball, causing it to accelerate to a high speed (N2). The moment the ball is released, this external force stops once the ball reaches the same velocity as the pitcher’s hand. Now, the force of gravity is the only force acting on the ball. The force of gravity is unbalanced and in the downward direction, this causes the path of the ball to bend slightly downward as it travels towards the batter. The ball exerts a force on the Earth equal and opposite to the force of gravity (N3); again, due to the mass of the Earth, the effect on the Earth is negligible (N2). In the horizontal direction, there are no net forces, so the ball moves at the same speed and in the same direction as it did when it was released by the pitcher’s hand (N1). It continues until it reaches the plate, where the batter swings the bat and hits the ball. The bat exerts a net force on the ball, causing it to change both speed and direction (N1). On impact, the ball’s velocity is reduced to zero (this is a large deceleration) (N1 and N2). The force of the bat then causes the ball to accelerate and move in a new direction (N1 and N2). The ball exerts the same force on the bat (N3), which causes the bat to slow slightly as the batter finishes the swing.

Explanation: