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# Jeremy Walther

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Gravity

## Physics of a pushup

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 we

## 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

## Popcorn

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 ultim

## Clouds

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 cl

## Astroids

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 fin

## Firearms

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 mor

## Physics of motorized bikes

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

## 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 forw

## 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 d

## Gravity

I watched a cool lab video on a professor giving a visual representation of gravity.  The idea of gravity has always been pretty easy for me to understand and easy to use in equations but where I begin to lose that understanding is when we leave earth and look at how it holds everything together.  How space is constantly expanding but these planets, moons and stars are constantly effecting each other.  In this video you get to see how gravity really makes these things work together to make space

## Dimpled Golf Balls

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 ve

## Soccer shot

People who are new to soccer almost always begin kicking the ball with their toe.  It seems like the best way to shoot because of how much power you are able to gain.  What people don't realize is the control and accuracy that is lost when this happens.  The best way to hit a ball for both power and accuracy is with the inside of your foot because of the major increase in surface area you are hitting the ball with.  Kicking a ball with your toe makes it much more open to have spin that may be un

## Physics of Karate

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

## Phyiscs of a Paper Airplane

Paper airplanes are something almost everyone has made but most people don't really think about ways to make it better and why some are better than others.  The main factor in creating a successful paper airplane is making sure it is as aerodynamic as possible.  Limiting the amount of factors to create resistance will result in a more successful trip.  This includes making a tail that air will glide right over instead of getting trapped on.  The two forces acting against the plane in flight are

## 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 translati

## Physics of swimming

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

## Physics of battlefield 1

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

## Physics of Catapults

Catapults are ancient weapons known for doing lots of damage from a far distance.  But how can a simple machine launch such big objects so far?  It comes down to the way the machine is built in which it creates large amounts of potential energy by either twisting a rope or flexing wood.  This potential energy is then transferred to the object when it is released.  One of the most common catapults is the ballista which is basically a giant crossbow.  In this the potential energy is stored in both

## Waves

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 differen

## Physics of bball

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 calcul

## Physics of solar energy

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

## Physics of a Frisbee

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

## Water bottle flip

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 rol

## Bulletproof Vests

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 t

## Physics of Fifa

A lot more work goes into creating a more smart life-like video game each year including Fifa.  A major break through in Fifa 14 was that they finally figured out how to make the ball sail smartly through the air. The engineers working on the physics of the game finally found the problem that was making the ball look like it was just shot in a linear path.  They found that their drag coefficient was broken.  This models air resistance  and affects the trajectory and speed of the ball when it is

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