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Everything posted by jrwalther

  1. jrwalther

    Week 3

    This week I focused on chapter 5 in Mechanics. This included momentum and impulse, conservation of linear momentum and center of mass. Areas that went well for me were momentum and impulse and conservation of linear momentum. What helped me to really understand these two topics were first understand the graphs that went along with them. This included Force vs. Time graphs showing the impulse to be the area under it. These graphs gave me a better understanding of what I was solving for when I got to problems. Center of mass was the topic I had the most difficulty with. However p
  2. jrwalther


    Throughout my life I have heard many rumors of asteroids hitting earth or the moon but I've always wondered what kind of damage an asteroid could really cause. The size of the explosion would be most impacted by the kinetic energy of the object that caused it. This would mean that the mass and the velocity of the asteroid would be the main factors in the damage. The average speed for asteroids approach either the earth or the moon is around 17km/hr. Now that we have the speed, how can we find the mass of an asteroid traveling that fast through outer space? Mass is calculated through the d
  3. jrwalther


    When put into its simplest terms, guns are not very complex machines. The goal is to deliver the maximum destructive energy with the minimum amount of energy to go to the shooter. Better more expensive guns will do a better job at accomplishing this task. However, conservation of momentum is true in guns as well. That means that the momentum delivered to the target still has to be equal to the momentum felt by the shooter. This is felt through the recoil of the gun. That is why bigger more powerful guns will have a bigger kickback on the person shooting it. The goal of a firearm is als
  4. jrwalther


    The physics behind clouds can actually be a whole profession. It turns out clouds are much more complicated then most people may think. At the base of it, clouds are made up of microscopic water droplets and or tiny crystals of ice. These droplets are initially formed from condensation onto the nuclei then the air is supersaturated. This happens when the air exceeds a critical value of condensation known as the Kohler Theory. These condensation nuclei are a big part and are necessary for cloud droplets to form. In warm clouds, larger cloud droplets fall at a higher terminal velocity; be
  5. jrwalther


    Popcorn has lots of physics behind the little pop. Until recently, popcorn had only been studied for it's chemical properties and never the physics behind why it pops the way it does. It comes from the fact that their is water in the kernel. When it is heated above 100 degrees Celsius, the water turns to steam and expands inside the kernel. It continues to expand until the shell can no longer support the pressure and it eventually pops. As soon as it pops, the starch cools it down and ultimately turns it into the white flake of popcorn.
  6. jrwalther

    Mafia 3

    Mafia 3 is a new open world game on the market and is featuring some pretty cool physics. One of the main focuses for the developers was the driving. It is crazy to see how far video games have come and Mafia 3's driving is a great example of that. The game takes crashes into account when the player is controlling the car. Crashes now have a big affect on the handling of cars. The game also offers two modes of driving, arcade and simulation. Arcade is similar to most video games in which driving is very easy and unrealistic. Simulation however is basically a driving simulation in which
  7. Marcus has been wondering why I always win in our 1 v 1 basketball games and their is lots of physics behind it. The first part of my success is how high I am able to jump. There are horizontal and vertical components to jumps and being able to shoot and or block shots during the top part of the flight plays a major role in winning. I also am able to jump higher giving me the ability to have a longer hang time. This increases the time during the top part of my flight. The equation to calculate my time during the top period of the flight is d = V1t — 0.5g(t)2
  8. jrwalther


    Waves have a surprising amount of physics behind them, and not the waves at football games. The simplest definition of wave motion is that it moves energy from one point to another. Waves are an oscillation of energy that travels through a medium. Their are tow main types of waves, one being mechanical waves. Mechanical waves travel through a medium and are then restored by restoring forces to reverse the work done. The other type of waves is electromagnetic waves in which the main difference is that they do not require a medium. They consist of periodic oscillations of electrical and ma
  9. Javelin throwing as it can be implied is largely dependent on the throwing angle. While it seems as if it should be like any other activity where 45 degrees is the optimal firing angle, it is not that case. Wind speed and direction have a huge dependence on choosing this angle. The strength and speed that the thrower can release with is also a huge factor. When studied it was found that some of the best javelin throwers in the world were actually releasing at a angle lower than 45. The optimal angle with average strength and wind speed factored in came out to be around 30 degrees. At thi
  10. jrwalther

    Week 2

    This week I studied chapter 4 which included work, energy and conservative forces, conservation of energy, and power. I found however that I spent the most time learning and working on conservation of energy. Areas that went well for me included work and power. Work was mainly review and it was good to go back and solidify my knowledge on the topic. This was the same for power as I found I didn’t take many notes. Most of it was review and the questions seemed fairly straight forward. The topics that were more challenging was energy and conservative forces and cons
  11. jrwalther

    Week 1

    This week I focused on the first three chapters of Mechanics, the introduction, kinematics and dynamics. I focused more on dynamics as I feel that is the area I needed more work on but both were very helpful. Areas that went well included most of the projectile motion. Describing motion 1 and 2 were also just review as I knew almost everything covered. Circular and relative motion was a little harder but it made more sense the more I sat down with it and compared it to translational motion. It is very similar in how you calculate and derive expressions as well as equations yo
  12. I am a black belt and I always enjoyed the physics behind karate as they are often more complicated than most people first think. When two people line up to fight, they both bring a certain amount of kinetic energy to the fight. This is determined by their weight, height, muscle strength and also their physical health. The main principle behind karate is to use your body to channel this energy and make maximum use of it. It also focuses on how you can take away from your opponents with smart blocking a defense maneuvers. We can often base the power of these punches on F=ma^2. Since our m
  13. A golf balls dimples are often overlooked as just being a design that someone decided looked good when in fact they play a major role in the flight of the golf ball. Ultimately, the dimples increase the drag of the ball slightly. But another big effect is that they increase "Magnus Lift" which is a lifting force experienced by rotating objects travelling through a certain medium. This lift is present because the ball often has backspin when it is driven with a club. Golf balls flights are very different from most objects as they don't follow an inverted parabolic flight. Their flight can
  14. Bulletproof vests are becoming much more common as they are becoming very easy to conceal. People are able to wear them under shirts and jackets and no one would ever know. They are very widely used in the military and police and law enforcement work. The vests are designed to disperse a bullets energy in order to minimize the blunt force trauma. Their are a couple different types of body armor. One of which is heavy body armor and is made of strengthened steel plates. The only down side to this is that it is obviously very heavy and not always convenient to wear. We are finding that to
  15. The are two main factors that affect a Frisbee during flight. Gravity accelerates the object downward at 9.8 m/s. In the air, lift and angular momentum act on it. Lift is created because of its shaped surfaces while it travels through the air. The reason a Frisbee flows so clean and far through the air is because the air flowing over the top of a Frisbee is much faster than the air flowing beneath it. The Bernoulli Principle also describes why is maintains this flight. It says how their is lower air pressure on top of the Frisbee than beneath it causing it to rise. This principle is als
  16. The water bottle flip challenge became very popular very quick but it is not just luck in getting the bottle to land upright. When the bottle is moving through the air during its flip, the water begins to climb the sides of it. This causes an increase in it's moment of inertia which in return, decreases its rotational speed. This is very similar to a diver who extends his arms and legs in order to slow his spin or an ice skater. The amount of water inside of the bottle also plays a major role in the success of it landing upright. If the bottle is full, the water would be unable to climb t
  17. Their are many factors that make a yo-yo spin showing they are actually more complicated than people may first think. Gravity is an obvious force as it is what pulls the yo-yo down. Friction is the reason that it unwinds and returns. Without friction the yo-yo would not spin nor would it return to the starting position. When it is at this starting position it is containing the potential energy to fall and spin. This is then converted into kinetic energy when it starts its trip. The yo-yo has the most kinetic energy when it is at the bottom and all the potential energy has been converted.
  18. The brain goes through lots of weird stages and experiences while sleeping that are very different from when you are awake. For one, the brain waves slow down dramatically. When awake the brains frequency is around 30hz and that drops to less than 3.5hz when the person falls asleep. There are around 5 stages of sleep every time you go to bed at night. The first stage includes a very light sleep while the second becomes slightly deeper. The third and fourth stages are the deepest part of it and the fifth stage is where dreaming occurs and their is an increase in heart rate and eye movement
  19. Video games are becoming more and more physics based in order to create a more realistic gaming experience. Battlefield 1 is one of the biggest first person shooter video games out right now and they did not forget about the physics. In call of duty sniping is very different from battlefield. In call of duty their is no bullet drop so if you aim at someone and shoot you kill them. That is not always the case in battlefield. They take into account bullet drop and drag. That means when using a sniper from long range you often have to aim above the person you are shooting at in order to acc
  20. I think that everyone knows how a hot air balloon works in theory but what are the basic physics behind it? The basic concept of it is that it blows hot air into the large balloon at the top to create buoyancy which eventually causes the balloon to lift. The air inside of the balloon is ultimately less dense than the air outside and this difference in density is also what causes the balloon to lift. The principle behind this lift is called Archimedes principle. This states that the upward buoyant force exerted on a body is equal to the weight of the fluid that the body displaces and acts i
  21. Push ups are probably the most common form of a workout you will see. They are easy and can be done almost everywhere, but how good of a workout are they actually giving people? There are different ways to do a push up but when done correctly, most people will be lifting around 65% of their body weight. This would be when someone is doing the standard position of having their feet kicked out. When a push up is performed on the knees instead of feet extended, we see that the amount of body weight they are lifting goes down by around 15%. These percentages show how push ups can also be conf
  22. Humans are clearly not as well suited for the water as we are for land, just look at a human body. We can't hold our breath for very long, and we get very tired very quickly in water. The main reason for this is the difference between the water and the air. The biggest difference between the two is that water is much more dense. When a human walks on land, the main thing your body has to do is work against gravity and then friction between our feet and the floor. Air resistance also becomes a bigger factor as wind increases or we pick up speed. The main force opposing a human in water is
  23. Solar energy is a growing demand in the United States as more funding has allowed this energy source to become much cheaper and more available to the average person. They are converting the suns energy into electricity using solar cells. This relies on the photoelectric effect which is the ability of matter to emit electrons when a light is shone on it. Silicon is a semi-conductor which makes it a key ingredient in making solar cells. Sunlight is composed of many photons and as these hit the silicon in the solar cells, they transfer the energy into loose electrons. This knocks them right
  24. Video games are constantly progressing in terms of how real they are becoming and the graphics. Part of these games becoming more realistic is the implementation of physics into them. The purpose of them is making everything appear more real to the viewer as if they were actually in the game. One big part of this is ragdoll physics. This is where bodies in video games appear more and more to have a realistic bone structure and similar joint movements as an actual human body. This includes bodies as people are killed and fall to the floor. As we see bigger video games being made, we see lo
  25. There is surprising a lot of physics that goes into a simple motorized bike. Even something simple on it like the weight of the tires. They are very important and in many cases can be the difference between you flying or stalling. This is because of leverage on the bike and the wheel is basically just a round lever. That means that the bigger the wheel and the more weight, than much more power is needed to move that wheel. This could be needing a bigger motor as a whole or may just slow the bike down. Another factor is the friction that goes into these bikes. Friction drive can have bot
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