# JesseLefler

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## Blog Entries posted by JesseLefler

As I'm sure many of you know eating sunflower seeds is a very popular task and one that is full of physics. Such as when you are biting down on the seed to crack it you are putting a force down onto the seed that is needed to crack but did you know that the seed is putting a force onto you. Indeed the seed is putting a force onto you called the normal force. This helps allow you split the shell. Now when you spit out the sunflower seed you are doing a kinetic equation that will affect the distance that you are able to spit the seed. Such as if you want to spit the seed farther you have to give it an initial velocity. Then this in turn will give it a larger displacement and will result in a final velocity of zero because the seed will have landed on the ground. This is the physics involved in spitting out sunflower seeds.
Throughout the Iron Man franchise, tony stark uses an arc reactor to stop shrapnel from piercing his heart, but how is this done. Well to begin with, when yinsen attach a magnet tostark's chest to use the laws of magnetism. By having the electromagnet facing the south side, it allowed the shrapnel to stop moving towards his heart and move still facing the magnet. Even still when stark made an upgraded arc reactor and told pepper to help him fix it into his chest. When pepper removed the magnet while trying the shrapnel continued its course. However when she put the new reactor in, it acted as an amplified magnet by completely stopping the shrapnel while still being mobile.
This spring break I got to fly down to Florida to visit my friend Henry! Henry is a big surfer so while I'm down there I'm going to get to learn to surf along with him. With break now approaching, i figured it would be a good opportunity to look into a little bit of the physics of surfing! First there is a lot of basic application such as the fact that the force that the board exerts on the water, is exactly equal to the force the water exerts onto the board. However as a researched more I found there is more complexity to it than I had realized. One major principle that plays in buoyancy. Buoyancy is the ability to float which is due to the density of the board. Another reason that board is able to so easily glide across the water is due to the surface tension. If you've ever gone skiing or tubing, you may recall that when you fall off the water is seemingly hard. Well the reason for this, is because the molecules that make up water are attracted to each other, therefore their bonds are very strong at the surface. Finally, some of the basic forces play into surfing. Gravity is what keeps the surfer on the water and it pulls it down, just as the normal force, equal in strength pushes back up from the water. Then there is also the frictional force from the water between it and the board. However this is attempted to be kept at a minimum, which is why surfers wax their board to create a very smooth surface, decreasing the amount of friction. Obviously there is a lot of physics involved in surfing and I can't wait to give it a try next week!
When riding a roller coaster, gravity is one of the main forces. When the cart on the roller coaster travels to the top of the hill, it’s the acceleration due to gravity that brings it back to the start. When the cart gets to all the way up to the top of the hill, gravity ends up pulling it down. The cart starts at a slow pace but gets faster as it approaches the bottom. As it begins to climb to the next hill, the speed slows down. This is because the acceleration due to gravity is 9.81 m/s^2. As the roller coaster cart begins its fall from the lift, its velocity increases which causes the cart to gain kinetic energy. So therefore the faster the cart moves, the more kinetic energy it gains.
In the upcoming Olympics, curling is my favorite sport to watch. Although many people find it boring to watch I think it is very interesting to see how it all works. The stone that is being slid down the ice is very heavy so that it can slide down the length of the ice without slowing down. The velocity of the stone is only a few meters per second. Before the game begins the force of friction is lessened by spraying water on top of the ice which freeze into little pebbles of ice that help the stone move down the ice. Lastly the people who are brooming help this as well because it rids the dirt from on top
In the movie Furious 7 there was a really cool scene where they dropped their high end cars out of a military plane with parachutes with the drivers in them in hopes to land on a road and continue driving. To shoot the scene they actually did it dropping two cars out at a time with parachutists following on the way down with cameras. At 12,000 feet the skydivers had to follow the cars at the angles needed and dodged falling debris. The shooting for this movie not only took caution and creativity but a knowledge of physics as well.
If you ever played any type of fighting game you've probably witnessed at some point in time that you are mashing every button to improve your chances of winning. The action of button mashing involves quite a bit of physics. For every push down of the button physics in involved, starting with the press of the buttons for each time you push the button down the button applies the same amount of force back onto your finger. That is called the normal force. Every time the button comes back up to its original position it is most likely due to the fact that there is some kind of spring involved. Springs are commonly involved in physics when dealing with forces. Overall I hope you learned something and maybe next time you're playing a fighting game or any type of game that involves the pressing of buttons you'll remember this little reading.
A handful of magnets are found on almost everyone's refrigerators at home. But how exactly do they work? To begin, the magnets on my fridge stick to it from both sides. When I attempt to make other metals stick to it, they simply fall. Therefore, the fridge must be magnetic attractable, meaning that it will be attracted to either side of a magnet and becomes polarized by the magnet. In addition, there are invisible magnet field lines on the magnet, flowing from north to south. The pictures of attached to the magnets between the magnet and the fridge only stay up due to the strength of the magnet. This explains why some of the magnets will not hold some of the heavier papers.
In the recent installments in the captain America movies, we see the captain using his shield to knock out the Nazi's during Wii but how doesn't it kill them. as we have seen in the movies when he throws his shield hard, newton's third law states that the amount of force is equal to the thing it transfers its energy to. so as the captain throws hard, the shield should have enough force to decapitate the enemy. also when Peggy shoots cap's shield, it makes a large vibrating sound. this is because the lognioitutional waves in the combustion form a mechanical wave, which is moving left and right in terms of the wave pattern. thank you for listening in the physics in captain America
I played soccer for about 3 years, and never understood that physics applies to all aspects of the sport, as it does to every sport. For example, kicking the ball into the air is an example of projectile motion. The ball is launched at a certain angle above the ground, or the horizontal, and lands back on the ground. During this entire time, the ball is being acted upon by gravity, causing the acceleration to be 9.81 m/s^2. Also, when the ball reaches it's maximum height, its velocity is 0 m/s. Lastly, Newton's 1st Law states that an object at rest stays at rest, and an object in motion stays in motion in a straight line at constant velocity, unless acted upon by a net force. This law applies to soccer, because when a ball is kicked but does not leave the ground, its velocity decreases as the time and distance increase, because it is being acted upon by friction, a net force.
After learning about Newton's 3rd Law, I thought about tug of war. I now know that when someone on one side of the rope is pulling on the rope, the force the person is applying to the rope and the force the rope is applying to the person are equal, no matter how hard the person is pulling. However, although the magnitude of the forces are equal, the direction of them are opposite, since the person is pulling the rope towards him/her and the rope is pulling away from the person. Also, I look can look at the net force between someone pulling on the rope with 200N and another person on the opposite end pulling with 100N. The net force of these two forces would be 100N towards the person pulling with a force of 200N. Lastly, due to the solution of the net force, this shows that the forces aren't at equilibrium because the net force isn't at zero.
Last year I was involved in the Dodge for Josh Dodgeball Tournament. This tournament raised money for the Josh Rojas Foundation. This event proved how physics can not only be fun but at times can also be painful. In the game of dodgeball the entire objective is to create and form collisions. In this sport there are two typees of collisions, inealastic and elastic. One can witness the collisions by watching a player get hit by a ball or when two balls collide into one another. IN an elastic collision, the total momentum and kinetic energy are both conserved. In an inelastic collision, the two objects move as one object and one mass. In this collision the momentum is conserved meanwhile to kenetic energy is being converted into internal elastic potential energy. The remainder of the kenetic energy is then converted into heat and sound energy. This tournament went by too fast but I guess that time truely does fly by when your having fun!
I am a horrendous driver. Perhaps reviewing the physics of driving will somehow make me a better driver. There's probably some sort of correlation between driving a car and all the other units that I've learned in physics, but the only unit I can think of right now would be the momentum and impulse unit, coincidentally one of my least favorite units. First of all, momentum is the equivalent of an object's mass times its velocity. So, if I wanted to find the momentum of my Mom's Nissan Ultima on a snowy day, I would take velocity of the car, .01 m/s, times its mass, 3000 kg, to get a momentum of 30 kg x m/s. Next, the impulse of an object is measured in several ways, including finding the change in momentum. If the momentum of my mom's car shifts to 20 kg x m/s, then that means to find the impulse of the situation, all I would have to do is subtract the two values, to get an impulse measurement of 10 Nxs
Some people might say that snow or rain or other forms of bad weather would be the easiest way to cause people to drive slower and safer, but in reality a police officer sitting on the side of the road is the easiest way to make everyone slow down. You will never see a more drastic change in people's driving behavior. A person could be going upwards of 80 mph but the second they realize their is a police officer, they immediately slow down usually to below the speed limit to guarantee they don't get pulled over for speeding. The radar guns police use, uses physics to help find out if the driver is going too fast. As the police officer aims the radar gun at cars passing by, the gun sends out radio waves toward the car. Then, the radio waves hit the car and bounce back toward the gun. The gun then measures the frequency of the returning waves, so the faster you are going toward the police radar gun, the higher frequency the waves will be. This concept uses a lot of physics including radio waves, frequency and also the Doppler effect. Since the car is moving toward the gun, the frequency of the returning radio waves will be much higher.
My neighbor owns a giant trampoline that my brother and I use quite often in the summer time. But at the moment it is covered in snow so rather than actually using it I can think of all the ways that physics is involved in jumping on a trampoline. Newton's 3rd Law is a large part of jumping on my trampoline because the law states that all forces come in pairs. For example, when I jump up and down, I push down on my trampoline with the same magnitude but opposite direction that is pushes me up with. This allows me to accelerate upward and the higher I go, the more I push down on the trampoline and it pushes back on me. Friction is also involved in jumping on a trampoline since there is not much to keep me from slipping. If I misplace my feet in any way, it is likely that I will fall do to the lack of friction that is between my feet and the trampoline.
For volleyball, my coach encourages people to jump rope in order to get "fast feet." As I was jump roping, I realized all of the physics that plays a role in this. I thought about how we are in the waves unit and I was creating a standing wave as I did my exercise. Afterwards, I wanted to calculate my velocity as I was jumping so I estimated that it took me 2 seconds for the rope to go around one time, and the distance of the rope was about 4 meters long. Using the equation velocity= distance/time, I could calculate that my velocity was 2m/s. Also, the force of gravity plays a role in jump roping as well. Gravity allows people to come straight back down after they have jumped into the air... which makes for a very strenuous exercise if done for even just a few minutes. There is physics to be found all over the place!!
A slinky is an extremely fun toy if you are 3 years old, or even 83 years old! The way it transfers energy back and forth throughout it is very similar to a wave. A wave can either be longitudinal or transverse, but in this case, a slinky is like a longitudinal wave. It bunches up at some points, but then expands out with different distances between each metal ring. Waves are found in every day life such as jump rope as well. As you spin the rope constantly around, it represents half of a wave. If you were to play the "Jumping over the rope game" as we used to call it in the olden days, waves are traveling through that rope even more. As you get a steady pace on the rope, more waves are in it. If we wanted to find the speed of the rope, you could use the equation v=fh( h=wave length). You would measure the rope and then calculate how long it is and how long it would take for the wave to hit the crest 10 times. This would give you the frequency and wave length of the wave. Waves are every where and can be tons of fun!
Gravitational force, or the force of attraction between an object and the Earth, has an impact on every element of Volleyball. Whether you are serving, bumping, or spiking, gravity will affect every interaction you have with the ball. Spiking: When you spike a volleyball, you have the opportunity to deliver a crushing offensive blow to your opponent. When spiking, you exert a downward force on the ball so that it falls rapidly on the opponent's side of the court, making it very difficult for your opponent to return the ball. Gravity works in your favor when you spike, because it also exerts a downward force that makes the ball fall to the court floor. For this reason you do not necessarily have to exert tremendous downward force to spike effectively, because gravitational force is also acting on the ball in the same direction. Digging: When digging a volleyball, you are exerting a sharply upward force to prevent it from hitting the ground. However, gravity is exerting a downward force on the ball, and if you do not account for this you will not hit the ball high enough to prevent it from hitting the ground. To account for this, bend your knees low to generate force with your legs, when digging. This will ensure that you hit the ball high enough for your teammates to get in position.
Work: Work is when a force moves an object. In Volleyball, the force is the player and the object is the ball. When the player hits, spikes, or serves the ball it moves in the direction in which the force has been applied. Hopefully, that direction will be over the net, when spiking or serving, and to the target when bumping. Velocity: Velocity is the speed of movement. You can figure out the velocity of a volleyball shot by dividing the distance your ball traveled by the amount of time it took to get there. So let's say you serve a ball across the net from the behind the serving line, 30 feet, and the ball takes 1.5 seconds to get across the net. To find the velocity you would divide 30 feet by 1.5 seconds, which would be 20 fps. So the speed of movement, or velocity, of your serve was 20 feet per second. The higher the velocity the tougher it is for your opponent to hit the ball back to you. Which means, the faster your ball is traveling the harder it is to return. Acceleration: Acceleration is an increase in velocity. Let's say you've just served the ball, it's gone over the net, and is falling to the ground. As gravity pulls the ball to the ground, it accelerates. If you gently lob the ball over the net and your opponent sends a hard spike back at you, that's another example of acceleration. The ball's velocity increased when spiked back over the net, by your opponent, therefore it accelerated.
Sir Isaac Newton, is said to be, the greatest English mathematicians of his generation. He laid the foundation for differential and integral calculus. His work on optics and gravitation make him one of the greatest scientists the world has known. Newton's laws of motion are three physical laws that form the basis for classical mechanics, and describe the relationship between the forces acting on the body and its motion due to these forces. Newton's laws affect every aspect of our life, therefore they affect volleyball, and every other sport, greatly. I'm going to inform you on just how the laws do affect volleyball. Newton's first law states that, " An object at rest will stay at rest, and an object in motion will stay in motion unless acted upon by an unbalanced force."  How does this affect Volleyball? : Newton's first law of motion affects every volleyball player who botches a serve and sends the ball snacking into the net. Every player who blocks a hard-hit ball from an opposing player feels the law's effect on her stinging arms. The server's hand, the net, and the blocker's forearms acted as an unbalanced force that stopped, or changed, the direction of the ball, the object in motion.  Newton's second law states that, " The acceleration of an object is directly proportional to the net external force acting on the object and inversely proportional to the mass of the object."  How does this relate to Volleyball? : Newton's second law of motion is a mathematical equation that explains the relationship between force, mass, and acceleration. Mass multiplied by acceleration equals net external force. A spiked volleyball creates a net external force that stings your hands when you stop it. But your hands hurt even more when you stop a ball hit by a different, stronger opponent. The harder-hit ball's higher acceleration rate results in a stronger net external force. Newton's third law states that, " To every action there is an equal and opposite reaction."  How does this relate to Volleyball? : Newton's third law explains that every action creates a force that is met by an equal reaction force from the opposite direction. When two objects interact, they exert a force on each other. The action force of a spiked ball meets the reaction force of a player's block. A team scores a point when the action force of a spiked ball meets the reaction force of the opposing team's court. The hard floor has more force than the soft ball, so the ball bounces off the court to equalize the reaction of the impact.  The next time you're playing or watching a game of Volleyball, think about all of the elements of physics involved. Without gravity, acceleration, velocity, work, and Newton's laws, Volleyball wouldn't be challenging at all.
Magnus Effect: The force exerted on a rapidly spinning cylinder or sphere moving through air or another fluid in a direction at an angle to the axis of spin. This force is responsible for the swerving of balls when hit or thrown with spin.  A soccer ball is basically a projectile that is flying through the air because of velocity provided to it by kicking the ball. The reason for a curve ball is because a player kicks the ball at a certain angle and a certain velocity. When you juggle the ball it can curve making the ball rotate to a different body part.  Drag occurs when the soccer ball is kicked and it travels through the air pushing while the air pushes back, thus slowing the soccer ball down according to the physics of soccer.  So when you launch the ball into the air the air will push back on it slowing the ball down, then the gravitational pull will bring the ball back to you so you can juggle the ball more.  Projectile Motion is best shown when the ball is kicked by the soccer player and it reaches its maximum height before it comes down. When the ball reaches its top height the velocity is equal to zero. So when you are juggling the ball and it comes at a specific height, it is because of projectile motion.
Soccer physics explains why the soccer ball curves, why it bounces, and how high it goes, as well as how the pressure in the ball affects the bounce or kick of the ball.  Newton's First Law: An object at rest tends to stay at rest and an object in motion tends to stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. That applies to juggling a soccer ball because the unbalanced force could be gravity or wind; but in this case it is the player's foot, head, leg, or shoulder. The player will use his or her leg to kick the ball into the air. Since the ball is at rest, it will continue to be at rest until the player comes in contact with the ball to start juggling. The reason for the ball to stop is friction, and Earth's gravitational pull. Newton's Second Law: The rate of change of momentum is proportional to the imposed force and goes in the direction of the force. This simply means, in the physics of soccer, that if the soccer ball has a lot of mass, it will require more force to accelerate. If the ball has little mass, it will require very little force to accelerate when the soccer ball is juggled.  Newton's Third Law: For every action there is an equal and opposite reaction. This means when you kick the ball into the air it will kick back at you just as hard. The only reason you don't feel or realize this, is because our legs have more mass, meaning more inertia, which is the resistance to move according to the physics of soccer.
Most popcorn lovers take for granted that a simple kernel of corn can metamorphose into a fluffy treat. But to a pair of French researchers, the popping of corn presents a powerful demonstration of how the laws of physics apply to everything — even a snack food. Until now, most research on popcorn has been focused on practical questions. Food chemists determined that the optimum moisture content of a kernel is 13.5% to 14% of its total weight. Food engineers concluded that the ideal shape for an unpopped kernel is a sphere. Plant breeders have reduced the rate of unpopped kernels by 75% since the 1950s. Virot and Ponomarenko aren’t interested in improving popcorn. They simply wanted to understand the physical origins of some of its most distinctive traits, like the forces that make kernels jump and the source of the iconic pop-pop-pop sound. Their fellow scientists were using a high-speed camera to take 2,900 pictures per second of physical phenomena, like a drop landing on the surface of water.  Known scientifically as Zea Mays Evereta, popcorn is the only type of corn that pops. Its kernels are more spherical than other corn kernels, and its pericarp — the hull that surrounds the seed — is a little thicker. The starch inside the seed is embedded in a protein matrix called the endosper.
Many martial artists aspire to be able to break through ice, brick and/or wood blocks simply by hitting such object with their hand. But how hard or easy is this? In reality it is far easier than one may originally think. Consider a one inch thick piece of pine wood, because of Newton’s Third Law, for every action there is an equal and opposite reaction, if we consider the hand/forearm and board as the whole system, there was on the whole system no net force that affected the impact. Therefore, there is conservation of momentum, which implies mV = (m+M)U. When m= the mass of the hand/forearm, V= velocity of the hand/forearm right before impact, M=the mass of the board and U=the velocity of the board fragments and the hand/forearm after the impact. It is known that it would take approximately 5 joules of energy to break the board, and with the equation E = ½(mMV2)/(m+M) (When E=energy needed to break the board) we can substitute the mass of the hand/forearm (about 1.3 kilogram) and the mass of the board (about 0.5 kilogram) into the equation to determine that V, the velocity needed at impact to break the board is about 5 meters/sec, or about 11 miles/hour.
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