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Snow Day Momentum

Conservation of Momentum Snow Day

My sister has recently decided to play softball this spring. She used to play, but has taken about two years off so she feels she may be a little rusty. She knew she needed to practice because the season is very near. Because we had the day off from school, she decided that this would be the perfect time to practice. So, she went outside and spent all day practicing her hitting with a wiffle ball and bat (and a batting tee to make sure she would be able to hit it perfectly).

It just so happened that I was able to get a video of one of her hits that perfectly demonstrated conservation of momentum.


The ball (m2) weighs 0.019845 kg and the bat (m1) weighs 0.226796 kg. I used LoggerPro to analyze the video and find the velocity of the bat and ball.

Using Logger Pro I was able to find that the initial velocity of the bat in the x direction was -0.02192 m/s and the bat's initial velocity in the y direction was -0.5455 m/s. I did not need to find the initial velocity of the ball because it started from rest, so the initial velocity was 0 m/s.


I also used Logger Pro to find the final velocities of both the bat and the ball. I was able to find that the final velocity of the bat in the x direction was -0.3874 m/s and in the y direction it was 0.04630 m/s. I also found that the final velocity of the ball in the x direction was 3.955 m/s and in the y direction it was -0.9642 m/s.



I then used the components found and equations learned in class to observe how the momentum was truly conserved throughout the system of the bat hitting the ball.

Conservation in the X Direction

Conservation in the Y Direction

Though these equations may seem to prove that momentum is not conserved, that is incorrect because the change in momentum results from the batting tee receiving some of the momentum. Thus, momentum really is conserved in this system.

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