# redsoxnation18

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## Blog Entries posted by redsoxnation18

Today sixth period i went to my friends 15 minutes of fame on swimming and i couldnt help but notice the physics involved. What i first noticed was the transfer of energy and forges in tyhe swimmers body to the water. From the energy put into the body, like food, that was transfered into the muscles to move through the water. The swimmer has to exert great force to increase his or her velocity in the water. Because of Conservation of Energy, energy is not lost but transfered from the swimmer into the water.

When the energy is transfered into the water it creates waves. With more enegy, it will make waves with a larger amplitude and a larger frequency. With less energy, it will make waves with a smaller amlitude and a smaller frequency. When diving into a pool, if the diver is more aerodynamic then they can reduce the amout of splash and waves produced when the hit the waters surface.

Gravity is also pulling down on the swimmers causeing them to sink at rest. Swimmers also must keep there lungs full to stay afloat and they must use energy in their muscles to fight gravity, although in water it is not as effective because the human bosy is 75% water.
I always look forward to skiing in the winter. Now that I have taken physics, I can understand different concepts of physics involved in skiing. I'd say the most prevalent physics concept besides gravity is the force of friction on the skier's skis. Although the coefficient of friction is only .05 it creates a large impact on the skier. This matters a lot when you are a skier going off of jumps needing the perfect speed. When the snow is wet and sticky, it can be much harder to keep speed and the friction between the skis and the snow is stronger.

Another concept of physics in skiing is projectile motion when a skier is thrown off of a jump with great amounts of momentum. Skiers launch off of jumps in perfect parabolic paths with momentum due to their mass times their velocity. When a skier is in mid air or just skiing, there is a lot of air resistance that can effect the flight of a skier after launching off of a jump.

Some more talented trick skiers spin and do flips spinning every which way. It looks like they are defying gravity and going against all laws of physics but they are only timing their continuous spin. They can tweak the spin to turn different ways. All laws of physics still are applying, theses skiers are just good at looking smooth.
Now that physics has come to an end, I understand a ton of information that will now always spark into my mind on a daily basis just by doing normal things. For instance when ever I throw a baseball I can't he but to think about different factors in projectile motion, like why does the ball fly the way it does and how can I get the ball to go the farthest with the right angle. Physics is everywhere and in everything and if you know a little physics then you will notice it a lot.

This year we learned about all kinds of physics concepts and we did all kinds of experiments. Some of my favorite topics were the topics that made me think like quantum physics. I also loved our projectile motion unit because at the end of the unit we got to build catapults.

My catapult was a mixture between a spring firing catapult and a trebuchet. The way a trebuchet works is by heavy weight dropping to rotate the catapult arm swinging a long sling and propelling an object. Instead of the weight, my group decided to use springs and bungee cords to put the arm and sling into motion with great force and it truly worked better than we expected.

The first test shot went over 60 meters, but being the way I am, I had to see if it would go farther. Joe F. and I changed the sling release angle to as close to 45 degrees as possible to see if it would make the softball go farther. We also experimented with other objects like apples and baseballs. The apples flew very inconsistent and the baseballs flew very far, much farther than the softball because off the less air resistance. We also tried making a baseball wet and heavy to see if it would change the distance but it didn't change much at all.

On the day of launch my group, Roxy, Joe, Andrés and I broke the school record and launched a softball a whopping 82 meters. I didn't now that it was going to go that far. I learned that if you put in 110% effort, anything is possible to achieve. This was a very fun and memorable part of my physics year. Thank you Mr. Fullerton for a great year of physics class!
From the projectile motion unit of physics class, i learned that a smooth ball has forces acting on it as it passes through the air: Gravity and the force of friction, air resistance. A baseball, on the otherhand has laces so the forces act a bit different. The baseball still has the force of gravity acting on it, although because of the laces the air resistance is more affective known as "Drag".

Drag has a very lage influece on a baseball. if the ball were to be thrown or hit in a vacume, there would be no drag, so the path of the ball would be a perfect parobolic shape. Although as all baseball players know, there is not a perfect parobolic shape. The drag slows down the ball in the air and, as seen in the graph above, the ball slows down and finishes its path earlier than predicted. Drag also affects a pitcher. When pitching the ball, drag can slow the ball 8-10 miles per hour in the 60 feet it travels.

On a spinning baseball, there is also a force acting on it known as the "Magnus" force. The magnus force describes the about of airflow past a spinning ball. For example, many people have questioned if a fastball can rise. And the answer to that is yes, only if the upward magnus force is greater than the force of gravity on the ball. Although this may not be possible for a human to preform. If you were to use a foam ball, and apply backspin on the ball, or an upward magnus force, then the ball will significantly rise. This video at 42:20 minutes explains and shows most of what i have said.

Finally, i have always been very curious to why a knuckleball dances. And for many years, even physicists have been baffled to why the knuckleball moves the way it does. This website, http://accessscience.com/studycenter.aspx?main=17&questionID=5579, explains well why the knuckleball dances. What i have found is that this occures because it doesnt spin as much. Because of the lack of spin, the laces create air pockets of low preasure around the ball. When the air rushes into the pockets, it pushes the ball into different directions making it "dance".
Surprisingly an outfielder needs to know physics to play good baseball in his position. Most people might think that catching a fly ball or a line drive is easy, but in reality it is not. Outfielders have a half of a second to pick up exactly where the ball is going to end up. The first initial reaction to a hit to an outfielder is, is it going to the left or right. The next fraction of the second must be used to see the exact velocity and angle the ball travels off of the baseball bat.

Baseball players, especially in the outfield, are physicists. They need to be smart enough to see the immediate velocity and angle of the ball off the bat from three-hundred feet away, incredible. Now realistically, outfielders have been practicing for years to track the flight of a baseball right after it hits the bat. Maybe it is a small exaggeration that they are able to read the velocity and angle off the bat. This video link is someone showing the physics behind tracking a ball in the outfield.

Not only is there physics involved in tracking a baseball, but also in the energy and momentum transfer. The batter builds up a lot of potential energy to then be transferred into kinetic energy when the ball hits the bat. When the ball is flying through the air and is accelerating towards the outfielder, it builds up speed and momentum. When an outfielder catches the ball, momentum creates an impulse of the glove moving backwards at a speed because of the mass of the ball and the amount of momentum.

Finally, the outfielder must throw the ball into the infield with the most accuracy and efficiency. For the best distance, the outfielder must launch the ball at 45 degrees. But for us outfielders we try to throw the ball on a straight line. This requires more speed and momentum to get the ball into the outfield as quick as possible. When an outfielder has already gone through equations in his head and serious calculations, when the ball is hurling through the air toward him it is extremely important to gain as much momentum as possible. This is only achievable if the outfielder takes three or four steps back and approaches the ball with extra speed to anticipate a crow-hop. A crow-hop is a skip like motion to obtain momentum to use all of your body mass to have a large effect on the baseball.

Once all of the above is achieved by the outfielder, they can then hurl a bullet of a throw into home plate for an amazing play from 350 feet away. Thanks for reading!!
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