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jwdiehl88

Roller Coasters, how do they move so fast without any motor pushing them? Energy!  More specifically kinetic and potential energy.  In the beginning of a roller coaster ride, there is an ascension to the top of hill.  The purpose of this is that as the roller coaster gets higher and higher up, it gains potential energy.  You could calculate this by doing mass times gravity times height.  After the the roller coaster reaches to the top and starts fall down, the potential energy is then transferred in kinetic energy, which moves the roller coaster.  Kinetic energy can be calculated by doing one-half times mass times velocity squared.  Energy can never be destroyed or created so the the roller coaster has a constant energy total.  Therefore kinetic energy can be also transferred to potential energy.  This is why roller coasters can move without any motor pushing it.  

jwdiehl88

Sledding

Sledding, a fun activity to do over the winter, applies to Newtons laws of motion.  Newton's First Law of Motion, the Law of Inertia, states that an object will not change unless it is acted on by an outside force. This means that an object at rest will stay at rest until a force causes it to move. Additionally, an object in motion will stay in motion until a force stops it.  When you are on top of a hill, there is no force pushing on you therefore you don't move. When you go down the hill, the force of gravity is on you therefore you have some velocity.  When get to the bottom, the force of friction slows you down until you stop.  Additionally, the acceleration of the sled is affected by the frictional force of the snow to the sled.  

jwdiehl88

Wi-fi

What is wi-fi? I used it all the time, but never really knew what it was. Wi-fi uses radio waves and sends out these waves to different devices to give them the power of the internet.  They send out around 2.2GHz - 2.4 GHz, These waves have similar frequencies as mircowaves.  These waves travel through the air, undetectable by the blind eye and they send out "information" to other devices.  The reason why people lose connection to their wi-fi after traveling some distance is that waves can only travel a certain distance.  Also the reason why wi-fi can be slow is because they can be blocked by interference by other waves crossing them. Additionally, there are certain amount of waves available, so the more devices connected on the wi-fi, the slow the connection will be.  

jwdiehl88

Washing Machine

Ten months from now, I have to do my own wash, so my parents are making me practice now.  Anyways, while I was doing my wash, I realized there is physics behind the washing machine rotating the the clothes around.  I realized that someone could calculate the centripetal force of the machine.  A person would have to mass the washing machine, then a person would have to measure the radius of the machine.  Then to find the velocity of you would use kinematics.  First you know the amount of time of the washer machine because you can set it up.  Then a person could calculate the rotational distance.  Measure how long it takes for one revolution.  Then with the rotational distance, it could be translate it to translation distance, with the radius known.  Then the person could find the velocity of the machine.  With that, the centripetal force could be found with mass times velocity^2 divided by the radius.  

 

washing-machine.jpg

 

jwdiehl88

Cello

Cello, the best string instrument, creates beautiful music.  But how does a cello create sound?  Well, sound is produced by the vibrations of the string, and these sounds resonate inside the cello.  Cello strings are fifths (five notes apart) and each string creates their own frequency when you place your finger down on different parts of the string.  As you place your finger down the fingerboard to the bridge of the cello, it creates a higher frequency.  As you place your fingers up the fingerboard, it creates a lower frequency.  Each string has different frequencies because of the thickness/wavelength of the string.  The more thick/smaller wavelength the string is, the lower frequency the cello creates.  Additionally, cello's have harmonics on each of the four strings.  Each at a difference frequency and when you play the harmonic, it produces a loud clear sound.  When you play a harmonic, this creates a shorter wavelength which in turn produces a higher frequency sound.  

jwdiehl88

Laser Surgery

Apparently, I have a mole that has a small chance to become cancerous, so I have to undergo laser surgery to get rid of the mole.  That lead to me to think, how is it possible that a laser could remove skin off a person's body, without hurting the surrounding skin.  So I learned that LASER is an acronym the represents Light Amplification by the Stimulated Emission of Radiation. So basically, lasers emit monochromatic (single color/wavelength) light that are designed to send ultra-pulses of light energy which is used to remove moles from the skin.  The heat/energy of the laser is absorbed by the pigment of the mole, it heats the mole up, and then he mole burns away.  Lasers are produced to have specific wavelengths of light that are being absorbed by certain pigment of the mole and not affect the surround skin cells.  When the laser energy is applied for the right length of time, at the right level of energy, and in the proper wavelength, the mole on the skin is selectively targeted.  This is why laser surgery is harmless to the surround skin of the mole.  

jwdiehl88

Breaking a Board

I used to practice martial arts and one day in our dojo, my sensei decided that we should have fun by breaking boards.  Although breaking a board seems impossible for a person who doesn't do martial arts, it is quite simple if we look at the physics of breaking a board.  For example, a person needs to generate a certain velocity to impact the board at a certain position.  A person should make the impact/position of where your hands end, up past the board.  Otherwise your hand will have a tendency to slow down when it reaches the actual position of the board.  Additionally, a person should position their strike on the board where the board it weakest.  For example if you punch the center of the board, it is harder to break it because that's where it is the strongest.  On the other hand, if you punch a board at the near an end of the board, it will break more easily.  It can still be very hard to break some boards because of how the thickness of the board.  As the board increases in thickness, you velocity of the strike has to be fast and more precise on the board. 

 

jwdiehl88

Hockey Shots

Shooting a puck, wrist or slap shot, requires a player, using their stick to apply a force greater than the frictional forces(very little, due to ice being relatively smooth) resisting the puck's movement.  Players have the ability to generate lift because all stick blades have a certain "tilt" angle.(the face of the blade is turned slightly upwards).  During the shot, the puck slides along the face of the blade and it is the tilt which allows it to be lifted off the ice surface.  Players who generate high speed velocity of their slap shot, has a large force and time of impact of the blade and hockey puck.  Players wind up for a slap shot, to generate a large force and then hit the hockey puck in a certain time.  Force * time = impulse = change of mass * velocity.  Therefore a large impulse equals a pretty large velocity.  Players who attempt wrist shots, have a less wind up because they want more accuracy then power.  The less force the player has on the hockey puck from the blade of the stick, means less impulse.  Therefore a lower velocity of the hockey puck relative to the hockey puck hit by a slap shot. 

jwdiehl88

Firing a Gun

Recently I was watching Point of Interest, a TV show, and I was thinking about what kind of physics are behind firing a gun.  I concluded that when the shooter shoots a gun, the force on the bullet is equal to that on the gun-shooter. This is due to Newton's third law of motion (for every action, there is an equal and opposite reaction).  The force of the bullet is equal to the gun-shooter due to the law of conservation of momentum.  A person with a gun have a combined mass M and the bullet has a mass m. When the gun is fired, the two systems move away from one another with new velocities V and v respectively.  Also, the person with a gun moves in the opposite direction of the bullet.  Therefore, the initial momentum is equal to the final momentum due to the law of conservation of momentum.  Since the net force is equal to the change of momentum, the initial change of momentum of the person and gun is equal to the final bullet's momentum.  Therefore, the person with a gun has a equal force and a opposite direction of the bullet.  

jwdiehl88

Tennis, a difficult sport to master, has many forces and transfers of energy acting upon it.  As a two tennis players rally a ball between themselves, it seems unreal as the ball flies to incredible speed between them.  This can be explained through Newton's law as the ball exerts a force to the racket, the racket exerts the same magnitude force but the opposite direction.  Also the ball hitting the racket or the ground experiences a inelastic collision.  This is why, it is hard for tennis players to hit a fast ball coming at them and to keep it in the court.  During the contact of the ball to the racket, it loses energy and to keep the energy constant, the players has to exert energy to match the incoming ball's energy.  Additionally, it seems impossible of the speed the ball flies and the accuracy some people have to keep the ball in court and high enough to above the net.  This is can be explained of the the force of gravity on the ball as the ball flies through the air.  The force of gravity helps the ball stay relatively low near the ground then in the air.  Also for the reason the tennis ball stays relatively low to the ground, the tennis ball has a drag force resisting from the ball going straight in the air. 

jwdiehl88

Swimming

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.  

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.

 

 

jwdiehl88

Shooting Your Grade Lab

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. 

 

Physics Lab.jpg

 

jwdiehl88

Curving a Soccer Ball

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! 

 

 

 

 

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