Running: When running the bases in softball, there is a lot more to it then the average person would think. While we run the bases, we are changing our momentum by applying more force, the force of friction, onto the ground which causes more force exerted on us because of Newton’s 3rd law. Applying more force in turn increases the base-runner's velocity.
Catching: When catching a fly ball or grounder, it is best to move with the ball and not catch it right over your head or right in front of you with stiff hands. By Newton’s 3rd law, for every action there is an opposite reaction, so we can decrease the amount of bounce the ball has on our hands. This is done by increasing the impact time. By increasing the impact time, we decrease the force making catching much easier and also much more effective.
Throwing: When throwing, there is a given and constant force exerted by the player onto the ball. To get a stronger and faster throw, we want the greatest change in momentum. A longer time in contact with the ball will give us a large change in momentum, also known as impulse. This idea explains the reason why us softball players are taught to reach our arms all the way back and follow through.
Collisions: In an intense steal from first to second base, or second base to home, many skilled base runners attempt to topple over their opponent to get called safe by a field umpire. This collision is considered an inelastic collision because the defensive player tends to fall on top of the offensive player sliding into them when they then both move forward toward the base. The initial velocity of the defensive player is 0 or at rest, and the initial velocity of the base runner is some value.