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jwdiehl88

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  1. jwdiehl88

    Swimming

    By jwdiehl88,

    Swimming is a popular sport that involves a ton of physics. The physics of swimming involves an many forces between the water and the swimmer. It is these forces which propel a swimmer through the water. In order to swim, a swimmer must "push" against the water using a variety of techniques. There are four major techniques used for swimming. They are, Front Crawl (freestyle), Breaststroke, Backstroke, and Butterfly stroke.  There are others, but ate used for recreational uses.  By moving his or her arms through the water the swimmer creates a thrust force that propels the swimmer forward.  This can relate to Newton's third law: every action as a reaction.  The swimmer creates a force in the water and the water creates a equal opposite to propel the swimmer.  However, there is a drag force created by the motion of the swimmer through the water. This force resists the motion of the swimmer through the water.  This is why, it is very hard to swim long distances because there is a friction force resisting you from swimming.  
  2. jwdiehl88
    Since I was watching football (Go Bills!), I was thinking about the forces acting upon a football in the air.  Newton's laws help dictate the pattern of all moving objects, including footballs.  The path of a football's flight is not random, it is the result of the physical forces of inertia, air resistance, and gravity.  Newtons first law of motion states that an object in motion will stay in motion unless acted upon by an outside force.  A football travels in a parabolic path because of outside forces like air resistance to keep the ball from traveling in a straight line.
    Newton's second law states that the total change of an objects motion is equal to the sum of all forces acting on that object. As a football flies through the air the forces acting on it are constantly changing, except gravity. As the quarterback releases the ball, inertia is the greatest force acting on it.  As the football reaches its highest point, inertia weakens due to air resistance.  Then gravity takes over and pulls the ball back towards the earth.
     
     
  3. jwdiehl88

    Shooting Your Grade Lab

    By jwdiehl88,

    On Friday, September 16, 2016, at 10:25 to 11:07,  Dan Fullerton presented a lab.  Unfortunately,the best 22 students of the high school, failed!  Thankfully, Mr, Fullerton allowed us to redeem ourselves by writing what the right answer was and why we failed.  This lab, Mr. Fullerton assigned to us was to shoot a projectile and predict where it would land.  By doing this we had to use kinematics.  We failed this lab for many reason. One main one was our lack of communication among our class. We didn't agree on measurements and we didn't communicate on answers. What we should of done was made four or five groups to figure out the answer and then at the end compare results.  Another reasons we failed was that we forgot to set our direction.  We didn't dictate what was positive or negative.  In our Y-component,  we assumed that everything was positive, but this was untrue.  If we made the down direction positive, then the height and acceleration is positive, however the initial velocity is negative.  Another reason why we failed, was that we had a variety of time of when the projectile was shot.
    When I redid this lab, the distance I found was 199.7 cm.  I found this by calculating the initial velocity of the X component and Y-component.  I made sure that I dictated the direction.  Then I used Pythagorean Theorem to find the initial velocity of the projectile.  Then, when Mr. Fullerton changed the angle and height of the projectile, I had to find the the X and Y velocity components.  I used the initial velocity, multiplied it by  cos (the degree) and sin (the degree).  Then I found the time in the Y-component, which is the same for the X-component.  Then I multiplied it by the new X velocity component to find my distance. 
     

     
  4. jwdiehl88

    Curving a Soccer Ball

    By jwdiehl88,

    Curving a soccer ball, seems easy enough.  Everyone is able to do it, on purpose or accidentally.  All you have to do is kick a soccer ball.  And yet, there is so much physics in how a person can curve a soccer ball.  The reason a soccer ball curves is because the kicker kicks the ball at a certain angle and velocity causing the ball to spin.  However, once the ball is in the air, it is really the air that is curving the ball.  This seems impossible, but the air resistant will curve and bend the ball in a way.  The Magnus effect is a lift force that causes the ball to curve through the air.   As a spinning ball moves through the air, it spins a boundary layer of air that clings to its surface as it travels along. On one side of the ball the boundary layer of air collides with air passing by. The collision causes the air to decelerate, creating a high-pressure area. On the opposing side, the boundary layer is moving in the same direction as the air passing by, so there is no collision and the air collectively moves faster. This sets up a low-pressure area. The pressure differential, high on one side and low on the other, creates a lift force (the Magnus force) that causes the ball to move in the direction of the pressure differential.  The force can applied to any direction, for example, backspin, topspin, and side spin.  Down below, I hope you enjoy the craziest curve shots! 
     
     
     
     
  5. jwdiehl88

    Eyes

    By jwdiehl88,

    I have horrible eye sight, so that's why I need glasses to see better.  And yet I never really understood how a mirror could make you see better.  Until last year, when we learned in physics of optical glasses.  Our eyes are concave, and the distance between our cornea to our retina is the focal length.  So the light that hits our eyes allows us to see images.  People who have twenty/twenty visions have eyes that aren't small or elongated and the focus is at the retina.  This allows people to see images clearly.  However people who have bad eye sight can either be far-sided or near-sided.  The people who are far-sided, have their focus behind the retina because the eyes are short, therefore convex lenses can fix this.  Convex lenses has a positive focal length which moves the image of a person far-sided forward.  People who are near-sided, have their focus in front of the retina because the eye is elongated. Concave lenses can fix that because tit has negative focal length so it moves the image back to focus.

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