Cvankerkhove

A very popular and interesting YouTube channel I watch is minute physics, where a guy does short videos on different concepts of physics. One video I have recently watched is about whether it is better to run in the rain or to walk in the rain. In other words, which choice will get you least wet. For one thing, the amount of rain that falls on your head is constant, as when you move out of the way of one rain drop, you move into the way of another rain drop. However, if you are the more horizontal distance that you travel, the more rain will hit you from the side. Therefore, the faster you move, the wetter you become. However, when you are trying to get from one point to the next, the amount of rain you run into will be constant (like a snowplow plowing a volume of snow, the speed it plows it does not change the amount). Therefore the answer is simple: Run. The less time spent in the rain, the better. Credit to minutephysics (at YouTube.com)

All I know, is once I made a zipline with an old rope from my tree house, went down it by holding on with my hands, and of course the weathered rope snapped. That's real life physics for ya

In this blog I will write about the internet phenomenon known as the water bottle flip. This action gained popularity in high schools and colleges around the world, and national talk shows, and even in the NBA! It's time to analyze the physics behind the so appealing flip. First of all, most of the bottles being flipped have a lower amount of water in them. They are certainly not full, about 1/3 to 2/5 full to be exact. This lowers the center of gravity, and therefore makes it easier to land the bottle. A higher center of gravity in a full water bottle would make the bottle want to tip over as the force of gravity is stronger and further from the surface. Secondly, when you flip the water bottle, based on angular momentum, the bottle will continue to rotate as result of inertia. However, the nonuniform water at the bottom of the bottle has a resistive net force down, and therefore a net torque that will cause the bottle to decelerate. As result, the bottle slows down when it reaches its upright position and has a great chance of landing opposed to a full bottle of water where the force of gravity is uniformly distributed. Finally, I will show you the video that started this whole bottle phenomenon. It is intense.

Its amazing when you think about how far the human race has come and been able to accomplish in the transportation industry thanks to physics.

Stephen Curry, a professional basketball player on the Golden State Warriors, is no doubt one of the greatest shooters of all time. Naturally, there is plenty of physics behind his sweet stroke. In this blog I will analyze different components of physics that relate to his game with the help from ESPN's Sports Science video on him. First off, Stephen Curry runs down the court at 10 mph (about 4.4 m/s) and can stop on a dime in approximately 1/3 of a second. This the implies that the deceleration of Curry when he gets set for a shot is 13.333 m/s/s. Because Curry has 87 kg of mass, a 1160 N force is required for Curry to make this stop. This means that this force is being applied to Curry's shoes as a force of friction by the ground and onto his legs. Furthermore, Curry shoots the ball, on average, at an angle of 55 degrees. Opposed to an average trajectory of 45 degrees by a taller player, Curry's higher arcing shot allows for him to shoot over taller defenders. Furthermore, his ball has a smaller initial horizontal velocity because it is in the air longer. Lastly, this higher arc increases the area in which the ball can go in by 19%! Lastly, Curry's release is wicked fast. On average the ball leaves his hand in .4s. This is the same time it takes the ball to undergo one full rotation, which implies the angular speed of the ball is 15.7 rad/s. To give a comparison, the average release time is .54s; Curry's crazy fast release is what makes him great.

On Monday, the defending NBA champions, Cleveland Cavaliers, played the runner up Golden State Warriors for the second time this season. The Cavs were looking for their 5th straight win in a head to head match up against the Warriors, however, the Warriors (with all 4 1/2 of their All-stars) handily defeated the Cavilers in this match up. The controversial play of the game was a Flagrant foul by Draymond Green on Lebron. The question is, did Lebron Flop? We can answer this question using physics and momentum. As we know, when two objects collide, whether an elastic or inelastic collision, momentum is always conserved. Therefore, if we calculate the momentum of the players before and after the collision, we can decide if Lebron flopped or if it was all from Draymond. According to an article from Wired.com author Rhett Allain calculates the momentum of the players. Based on the players listed masses and video analysis he found that this was the data: "LeBron before the collision = +548 kg*m/s LeBron after the collision = -264 kg*m/s Draymond before the collision = -362 kg*m/s Draymond after the collision = -290 kg*m/s" (Allain, Wired.com). Now if we use this data, the momentum before the collision was 186 kg*m/s in the positive direction, while after the total momentum of the system was 554 kg*m/s in the negative direction. Clearly this is not conservation of momentum so an external force was provided. This force was provided by Draymond legs pushing on the ground. So, yes, Lebron may have flung his arms, but Draymond certaintly did provided an extra force to push Lebron down.

Recently I watched the film 007 Casino Royale, the first installment of the James Bond series with the new Bond (Daniel Craig), and while the movie was very good (and equally dense) there were many inconsistencies with the real world, such as the statistical improbability of the cards, but this is a physics blog so I will talk about the physics of a certain action packed chase scene in the beginning. The parkour scene takes us through a construction site. One thing I noticed is that at one point when the man being chased jumps down an elevator shaft, uses the wall to jump back and forth, and I believe that the force of friction between his shoes and the wall would not be great enough to support his jumps. Also, there is a large explosion that happens very close to the villain, and the blast would have most certainly effected him, the momentum of the explosion would be enough to carry him through the air. Lastly, James Bond makes about a 25 ft jump, rolls and then falls another 10 feet onto a metal crate which he crushes. The impulse delivered to bond would have been enough to kill him, or at least knock him out. But he just shakes it off and the chase continues.

There is plenty of physics when it comes to playing basketball, from shooting a three pointer to dunking. In this blog I will assess the physics behind dunking a basketball. First off, you probably have to be a decent height, the shorter you are, the more force your legs will need to provide. Having a high vertical is the most important thing, however, for example Michael Jordan, one of the greatest dunkers of all time, had a 40 inch (1m) vertical. Now the initial velocity needed to reach this height (with the acceleration due to gravity at 10 m/s) is 4.47 m/s. Assuming the force your legs provide is over a time of .5 seconds, the acceleration is about 9 m/s. Given that Jordan was 100 kg, the normal force provided by the ground (created by his legs) is approximately 900 N! Clearly, there is some strong force required to jump and dunk, which is why you should never skip leg day, but more physics behind leg day another day.

Recently the iPhone game 8-pool has gained popularity as friends compete back and forth and there iMessage. Basically the game is a virtual version of billiards, and as result there is plenty of physics behind it. For one thing, because this game is virtual, friction of air resistance is non existant. Furthermore, while conservation of momentum is always conserved, in this game energy is also conserved between balls. The energy lost to sound and heat is not a factor, and therefore all energy is transferred into mechanical. Lastly, principles of conservation of linear momentum are present and shown as when you line up to hit a ball, it shows the resulting direction of the ball and the cue ball. These two directions will always form an angle of 90°, illustrating the principle of pool balls conserving momentum in both the x and y directions.

A clock is a very helpful invention and there is plenty of physics behind it. Today I am going to analyze he rotational motion behind a clock. First off, when any hand completes one revelution, whether it means a minute, an hour, or 12 hours, the angular displacement is 2(pi) radians or 360°. This of course allows us to find the angular velocity (w). If we are talking about an ideal clock that rotates at a constant rate, we can determine that the second hand travels pi/30 rad/s. Next, the minute hand travels pi/1800 rad/s. Lastly, the hour hand travels pi/108000 rad/s. The angular velocity will be the same on every clock, but the linear speed of the outermost part will be greater the larger the clock. Now this gets a little more complicated if we have a clock that ticks (which a lot do). The second hand does not travel at a constant velocity, rather it accelerates then decelerates, every time it travels one notch (pi/30) rad. On a certain watch I have, it takes about .3s for the hand to move one tick, meaning he acceleration and deceleration are about 9.3 and -9.3 rad/s/s. Clearly clocks are very complex but have some cool physics.

Don't worry Mike. That's for next time

I'd say the scariest part of catching a football is the possible change in momentum when a defender hits you from behind in the air!

So yes, the first quarter is coming to a close meaning that all who are reading this survived a quarter of AP Physics C. Congrats! In this blog I'm going to give a quick overview of the triumphs this quarter. This semester is mechanics, and so the course started with kinematics, the "easy" unit. We learned about how to utilize calculus to further the concepts of kinematics, how to take derivatives to find an instannous acceleration, or a integral to find the total displacement and so on. Next was dynamics, applied forces, and C level physics brought about the always ignored (and dreaded) air resistance. Using a differential equation, we learned how to derive an equation for velocity as a function of time (with resistance). Next came work, energy, and power. The major concept learned was that force= - dU/dx because work done over a distance is force x distance. Lastly, the final unit of quarter 1 was momentum and center of mass. Center of mass was not a major unit in Physics 1, however in Physics C we learned to get in depth behind proofs of why the center of mass of a uniform rod is L/2, using integral calculus. Overall, it's been quite a task, but I'm glad I got my work done and was able to expand my knowledge in the field of physics.

A very fun activity to do on a sunny day is jump on a trampoline. Fun for all ages, a trampoline makes it easy to get major air. What exactly is behind this mechanism of a trampoline flinging a person into the air? Well let's talk physics in terms of energy. Let's say that our reference level is where one stands on the trampoline. As soon as a person stands on a trampoline the webbing is stretched and sinks down to equilibrium. This is similar to our lab experiment of placing a mass on a vertical hanging spring. Now once a person stretches below equilibrium (by pressing down a force and/or jumping up) the fun begins. A person has a potential energy at the top of their jump, and this is converted into kinetic energy as they move, which is then turned into spring potential energy, when a person stretches below equilibrium level. This idealogy is the basic physical concept of a trampoline. With this knowledge a person can incorporate cool and crazy tricks to do on a trampoline.

Interesting post. Not to mention the fact that when kicking the ball with your toe hurts more because it is more force over a smaller space

All sports have a lot of physics to them, but one sport in particular I have noticed to demonstrate principles of physics is football. Watching the NFL, the Minnesota Vikings are my favorite team, and though they had a great 5-0 start, ever since the bye week they have been slipping. Here's the physics behind their struggles. The pass rush defense is weak. Viking blockers apply a force to the pass rushers, however, the pass rushers force is greater and able to overcome the resisting force. This causes a net force in the direction towards QB Sam Bradford, and as result he gets sacked. Furthermore, in the red zone, Bradfords passing has too much of a vertical component of velocity and not enough horizontal component. The ball is lofted and resulting in interceptions instead of scoring. Bradford needs to decrease that angle to score. Hopefully the Vikings read this post and start winning again!

That's good stuff! How much energy would it take to go over the top of the swing and make a loop?

So The Simpsons is one of my favorite shows of all time for it's hilarious characters and plots, and interesting story. Now cartoons are not always known for their strict following of the laws of physics (because sometimes it's just funny how fake it can be), but this particular scene I am about to analyze does a pretty good job of demonstrating a key concept: conservation of angular momentum. In this scene, a student (Ralph) is in great peril, and so Principle Skinner attempts to save him by sending a message, however, this escalates the situation as it leads to a giant crate at the docks dropping grand piano's. First, lets analyze the physics of these falling pianos. The crate appears to be tilted up at an angle of 45 degrees with the horizontal, meaning that the piano's are accelerating down the crate at about 6 m/s/s (assuming some friction). However, what is comical is that there appears to be an infinite supply of pianos as we see 20 something pianos fall out of the too small crate. Assuming a max amount of 20 pianos, and each piano at 5443 kg, the tension in the rope supporting the crate would have to be 1,100,000 N!!! Lastly, the Principle demonstrates conservation of angular momentum by running in a circular path around the crate. The crate then reacts and moves in the opposite direction. Because Skinner has an angular momentum in the clockwise direction, by conservation of momentum, the crate moves in a counterclockwise direction. This is also a representation of Newton's third law that for every force there is an equal and opposite reactionary force. Off course, Skinner's mass is so puny compared to the crates, it would not pin nearly as fast, but nonetheless, still hilarious.

Ever seen the movie ride along? Kevin heart fires a shot gun and goes flying in the other direction

Whether you notice it or not, there are fundamental concepts of physics on your way to the grocery store. For one thing, in an average car ride all three types of acceleration happen: acceleration, deceleration, and turning. Another thing, riding fast in a car helps me to understand concepts of inertia. When I was little, we would be traveling 50 mph down the highway, and I would throw a tennis ball in the air. The tennis ball moved with the car. I asked my dad why the ball didn't go flying to the back of the car. That was the moment I learned about the concept of inertia. Lastly, on highway 104, there is a very large round about turn. Every time we make this right turn, I feel as though I will fly to the left side of this car. Knowing physics, I now know that inertia is what makes my body feel that way, and the centripetal force of friction keeps me from doing so. I could even calculate the force felt by f=mv^2/r.

I've seen this demonstration before! Seems like a pretty fun class

Very funny show. One of my absolute favorites! Not sure their physics always matches up with our physics tho

Today in physics class we did a little something special; a fun activity investigating several crimes. Whether these crimes were really in the local area, or a figment of imagination, it was still interesting to pick them apart to find out the culprit. The first crime scene was a murder, murder by gun. We had to decide which gun did the killing and based on small pieces of evidence, and by knowing this gun we could match it up with certain people. We knew the initial height of the bullet (the exit wound) to be the height of the victims shoulder, and the final height the height of the hole in the wall. Using this displacement, the acceleration due to gravity, and the fact that the bullet traveled horizontally, the time could be found. Finally, using this time and horizontal displacement, we discover a velocity 30% as strong as the velocity fired, and the pieces match up. Secondly, a body was found dead at the bottom of a hotel after Alonzo Green supposedly tried to jump to the swimming pool. We have to decide if he jumped, or was pushed. Once again, using kinematics we can find the time it takes for a person to fall the given height. The given height could be measured with a diagram and a conversion scale from cm to meters. Once we have this time, we are given the max velocity of a 45 year old male sprinting to be 6.9 m/s, and this velocity will leave a person 2 meters short of the pool, exactly what Alonzo was. He jumped. Lastly, Evelyn Horton drove her car off a bridge when she supposedly was sabotaged by a raging driver. However, she may be just saying this to avoid embarrassment, and so we want to know which is true before moving in to a long term investigation. Once again, kinematics are used to find the time it takes the car to fall a certain distance, and therefore allow us to find the initial velocity when hitting and breaking the rail. Horton claimed that she decelerated at least 8.83 m/s/s before hitting the rail, however, with her given initial velocity, her final velocity with this acceleration would be to slow to make it as far as she did, therefore she snoozed. All in all, this was a fun activity that put a spin on our daily routine in APC, and the extra credit definitely made it competitive and fun

Hockey may be the most physical sport. Football is up there too.

In this blog I have finally decided to dwell on the much ignored physics of movies, specifically superhero movies. And while many of these movies ignore laws of physics for good reasons (some movies would be unbelievably boring if they did),it is still worth it to knit pick the physics of a great superhero. I am going to focus on the movie X-Men: Days of Future Past and I will focus on a certain scene with a certainly remarkable character: Quicksilver. This hero is a super speedster that can run up to speeds well over the speed of sound, and this remarkable scene implies Quicksilver to the most powerful superhero. Here's the physics on why. In the scene, everything slows down dramatically, while Quicksilver moves at a normal speed, and using his frame of reference, I calculated just how fast he was going. In the scene I timed a watched a bullet fired by a revolver to travel approximately 1 cm in 3 seconds with respect to Quicksilver's frame of reference. Assuming the revolver to be an average pistol, we can say that it's speed was around 400 mph, or 178.8 m/s with respect to real time. Now if the bullets travel about 0.0033 m/s in Quicksilver's frame of reference and they were really traveling 178.8 m/s, this means that Quicksilver's frame of reference is 53,640 times slower than the average person's. Furthermore, if we say that the fastest Quicksilver traveled in the video was about 15 m/s, his actual speed was 804,600 m/s (2366 times the speed of sound or Mach 2366)! Now lets talk about the implied powers with this speed. First off, Quicksilver's legs are incredibly strong, because legs apply the force to the ground that accelerate the body. If he accelerates to top speed at a .01 of a second, his acceleration is 80,460,00 m/s/s, meaning a force applied of of at least 80 million Newton's. Secondly, any touch from Quicksilver could be fatal. If he touches and moves a person's head even 1cm, the change in momentum on that time interval (say .001s and a mass of 5kg) would be 50 m/s(kg), and because impulse is the change in momentum, the force applied would be 50,000 N! That is a huge force, a concussion to the head to say the least; now just imagine if he punched a person at top speed! Lastly, the fact that Quicksilver's mind can perceive and comprehend the world 53,640 times as fast as we can shows just how powerful his mind has to be. Not only is a physical specimen, but we can imply he's intellectual superior by this fact. Now we know he is powerful, but now it's time for me to rant about why just about all of this is impossible. First off, lets talk about that fun thing called friction. Because Quicksilver accelerates so quickly, there would be a crazy amount of frictional force applied to his feet. At the speeds he is going, his shoes should probably wear off and burn to fire, but that what not be too convenient for our hero. There is also friction in the air called drag force. This force becomes greater at higher speeds, and if you want proof for that, stick your hand out the window of a car when going 10 mph vs 100 mph . One can imagine the air resistance Quicksilver experiences when accelerating and decelerating to these top speeds of 800,000 m/s. His clothes would probably blow right off, and luckily the directors ignored that too. Thirdly, there is a point in the scene when Quicksilver throws a plate, and in mid air it slows down to the speeds of all the other objects (as if it was thrown at Quicksilver's frame of reference, but traveled at real time). Any Physics student knows that by Newton's 1st law a body in motion tends to stay in motion, not decelerate at 80 million m/s/s! Lastly, the entire scene, Quicksilver listen's to Jim Croce's "Time in a Bottle" on a Sony Walkman, and even if we ignore all the sonic booms Quicksilver creates, one would have to understand that the song would have to be playing 53,640 times as fast as normal. If we assume the average angular speed of the tape on a Walkman to be 33.3 RPM, it would have to be traveling at about 2 million RPM for Quicksilver to listen, and maybe the 1970's gadget can handle that speed, but I wouldn't count on it. Anyway, if you have made it this far in reading my blog, thank you and congratulation, you made it through a movie rant! Now this scene is one of my all-time favorites, so click below and enjoy