91Ó°ÊÓ

Velocity is a fundamental concept in physics that describes how fast something is moving and in which direction. It's not just about speed, because velocity also considers direction.
If you imagine a car moving at 31 meters per second towards the north, its velocity is 31 m/s northward. When we talk about direction in physics, it matters a lot! This is why, in the problem provided, the initial velocity of the baseball is 31.0 m/s towards the pitcher, and after it’s hit, the velocity becomes -46.0 m/s, indicating it travels back in the opposite direction.
Understanding velocity helps us predict where something will be over time if it keeps moving at that speed. In this scenario, because of the change in direction after the baseball was hit, its velocity went from positive to negative, which is crucial for calculating the momentum change.

Force is what happens when objects interact. In its simplest terms, force is a push or a pull on an object resulting from its interaction with another object.
Forces make things move or stop moving. In this case, the bat applies a force to the baseball to change its velocity.
The exercise involves calculating the average (constant) force acting on the baseball during the short collision time by the bat. The force that changes the baseball's velocity can be determined using the momentum change and the time of contact. This is given by the formula \[ F = \frac{\Delta p}{\Delta t} \]where

• \( \Delta p \) is the change in momentum,
• \( \Delta t \) represents the time duration of contact.

In our problem, the average force came out to be \(-2233 \text{ N}\), the negative sign indicating the force direction is against the initial motion of the ball.

Momentum is all about motion. It represents the quantity of motion an object has and is calculated by multiplying mass and velocity. When the velocity of an object changes, so does its momentum.
In the baseball scenario, the change in velocity was crucial for finding the change in momentum.
The formula to find the momentum change in this case is:\[ \Delta p = m \times \Delta v \]where

• \( \Delta p \) is the change in momentum,
• \( m \) (0.145 kg for the baseball) is the mass, and
• \( \Delta v \) is the change in velocity, computed as \(-77.0 \text{ m/s}\) in the problem.

This brief alteration in momentum, occurring during the collision with the bat, has measurable consequences: it changes the direction and speed of the baseball, achieving a final momentum value that influences how forces interact. The exercise simplified by assuming the bat-ball interaction had a constant force over a short time span, thus making the calculations straightforward yet insightful.