APlusPhysics Blogs

Showing blog entries posted in the last 365 days.

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  1. Past hour
  2. How does a whistle work? In order for the typical whistle to work you need air streams. In order to get the high pitched noise that you hear coming out of a whistle you need the air steams to interact or cross paths. This is done through the round part of the whistle, as you blow into the whistle the air travels through the loop and up again (as seen in pic below) this allows the air to cross paths with the new air coming in. At this point where the air stream crosses itself again becomes a high pressure point and the air that escapes is what makes the noise. Whistle pitch and frequency depends on the length of the whistle, the longer it is the lower the sound will be. There are other types of whistles that work in a similar concept but vary slightly. The image below is the standard whistle that I am talking about.
  3. Today
  4. Recently in our APC physics class we have been doing electricity and magnetism and therefore our labs include creating circuits with wires, resistors, breadboards and batteries. I believe one of the most important things I learned from this lab was that licking a 9-volt battery gives you a shock. I thank Mr. Fullerton for teaching me this trick. When you lick a 9v battery, your tongue acts as a conductor as it is wet and therefore electrons are free to move, both ends are touching your tongue and therefore a mini circuit is created. If you feel a slight shock, that's good: your battery is all charged up!
  5. As basketball season has come to a close, it makes way for tennis for me, and there is plenty of physics in tennis. First off, the tennis racket itself has engineering to allow the ball to fly with maximum velocity. Many cords are woven in the foundation of the racket, the strings have a strong tension in them and as result the hard tension allows for a ball to bounce of the racket and change direction. The rackets tensions are rated in force, specifically pounds (maybe newtons in Europe). anyway that's just a little bit on tennis. There is plenty more such as kinematics and momentum, but that's for another blog.
  6. As basketball season has come to a close, it makes way for tennis for me, and there is plenty of physics in tennis. First off, the tennis racket itself has engineering to allow the ball to fly with maximum velocity. Many cords are woven in the foundation of the racket, the strings have a strong tension in them and as result the hard tension allows for a ball to bounce of the racket and change direction. The rackets tensions are rated in force, specifically pounds (maybe newtons in Europe). anyway that's just a little bit on tennis. There is plenty more such as kinematics and momentum, but that's for another blog.
  7. Yesterday
  8. Huh I didn't know that the paper on the outside would act as a wick, I always thought that the reason the wick didn't immediately burn on a normal candle is because it is surrounded, guess that is not the case.
  9. Very interesting, I always find optical illusions cool.
  10. The High School recently put on a musical production called The Addams Family, for stage crew we had to build the set which includes something called a fly system. On this production we had many parts of the set on the system in order to fly them in and out. For instance one of the bars held an entire wall that was used as a backdrop that would only let in small spots of light to resemble stars. This was moved often as the scene changed from inside to outside a lot. The way that the fly system works is a set of counter weights that offsets the weight of whatever is on the bar. As you can see above the weights are put on a platform that is connected to a long rope on a pulley system, however this pulley system is 1:1 so there is no mechanical advantage. Each weight weighs about 20 pounds, so on the large stack in the picture it is meant to lift something weighing around 320 pounds. The problem with trying to move something so heavy is that the bar is not going to want to move due to inertia as the mass of the system is double the mass of the object being lifted. Another problem that arises is that if we need to make a quick scene change then the fly needs to go up quickly. The big mass and the large speed give the system a lot of momentum that needs to be stopped carefully or else something may break.
  11. Last week
  12. Lots of wibbly wobbly timey wimey stuff here...
  13. Mr. Fullerton recently gave us a hand out explaining electromagnetism and how it directly relates to Einstein's Theory of Special Relativity. According to the theory, length and time are not absolute measures, but can be perceived differently based on the motion of the observer. This can be applied to current in a wire. Take a wire with no current flowing in it. As a whole, the wire is neutral as there are equal numbers of protons and electrons. When current flows through the wire, the electrons flow in a specific direction. The density of positive and negative charges in any section of the wire is the same, however, making the wire still neutral. Imagine a charged observer object moving outside the wire. The charges within the wire experience different motion relative to the charged object, so the separations of protons and electrons differ slightly from the observer's perspective, creating a difference in charge density, leading to a non zero net electrical charge, and therefore a net electric field. The charged observer sees the wire as having a net electric charge; therefore, it experience a magnetic force. It is crazy to think that the charged observer would experience a force simply because of what it perceives in the wire; even though the wire is neutral, it is not neutral to the charged observer. Crazy stuff.
  14. I've never heard of the silver egg illusion before. Very cool!
  15. I never knew that turbo systems pump more air into the cylinders of the car.
  16. I will definitely beat you in Jenga.
  17. So on the back of super cars you often find a spoiler. As a kid I always thought that a spoiler was just to make the car look cool but in fact it does serve many purposes depending on the positioning and type of spoiler used. One use of a spoiler is to push the air around behind the car as the car pushes through the air this reduces the drag force on the car. This application of the spoiler can improve gas mileage. Another reason why spoilers are seen on super cars is because when traveling a very high rates of speed it is often very difficult to control the car. By adding the right type of spoiler it can use the air that you are traveling through to push the back end of the car down, creating more downward pressure, this is know as counter lifting. This gives the car more grip that allows the car to have more power and control thus increasing performance. The car below is the mclaren p1, this is a car that makes use of a spoiler in order to keep it on the track and increase performance.
  18. So as we all know there is no gravity in space so, what would happen when you want to wring out a wet towel there? I fond this question very interesting when talking with friends so I thought I would take a deeper look into it. When you have a very wet towel and go to wring it out, the water is not just going to fall off like it does on earth. Instead because of the waters surface tension and lack of gravity in space, the water will float around the surface of the towel forming a tube shape around it. The water will stay like this until further actions are taken. I found this very interesting because you don't think of gravity effecting such small actions like wringing out a wet object until it is no longer present. After looking at this it would be cool to see how they get the water out of something super wet in space since you cannot just wring it out. The video below shows what happens when you try to wring out a towel in space.
  19. Off to a great start!
  20. Did you know that you transfer about ninety percent of your force upon a pedal of a bike into kinetic energy? Riding a bike is so simple but there is so much physics behind it. As you ride a bike there are multiple forces on you. There is a force of gravity downwards on you, so as you slow down, the force of gravity will push you and the bike down. There is also a drag force and frictional force acting on you and the bike. The drag force is the air resistance you feel when you go downhill. If you're going at a high speed with your bike then you can feel the air resisting you from going down the hill. Also you can't forget the frictional force between the tires and the road. Then there is a force pushing you forward which is caused by the work the person does by pedaling. As the person decreases its work then, the frictional force will be greater causing the bike to slow down. But if the person increases its work, the force going forward will be greater than the frictional force causing the bike to speed up.
  21. Earlier
  22. A common part of baseball is seen almost every pitch when the catcher moves his glove slightly when he catches the ball to try and convince the umpire the pitch was actually a strike, when really it was a ball. This is called framing, and when one really looks at the process, it is easy to see how strong and skilled a catcher must be to execute it. One of the best in the game at this is Yadier Molina. In the video below, take a look at how Molina totally redirects the tremendous force of a ball travelling over 80 mph and sinking down below the zone. The way Molina "sticks" the pitch on the corner of the zone led to this pitch being a strike, even though it is very clear it should have been a ball. He moves his glove up while barely moving backwards, meaning he absorbed and counteracted the downward angled force of the ball in a split second, and made it appear that he actually caught the ball at a spot above where he actually didnt. When one thinks about the serious force behind a major league pitch, Yadier's tremendous strength becomes even more apparent, as he appears to move his glove at will, even though it is being impacted by a projectile travelling at over 80 mph.
  23. Absolutely beautiful. And you put that first video together? Great dramatic musical selection to go with it!!!
  24. Could you create an invisibility cloak? I mean if it was possible it would be insane. But what if there exists a material that scientist created that allows it to bend light or an electromagnetic radiation of an object, giving the appearance that it isn’t there at all. Light is electromagnetic radiation, made up of vibrations of electric and magnetic fields. Natural materials usually only affect the electric component. However metamaterials can affect both the electric and magnetic field. Metamaterial is a material engineered to have a property that is not found in nature. They are made from multiple elements composite from materials such as metals or plastics. Physicists from the UK and Germany made one small device that made small objects invisible to near-infrared radiation and worked in three dimensions.
  25. The hovercraft hovers by creating a cushion of air with enough pressure to the weight of the craft and the passenger. The fan constantly blows air molecules into the cushion. The cushion inflates, and there are a couple of holes in the cushion that allows some air molecules to escape so the cushion doesn't explode from the pressure. The trick to get the craft to hover is to have the air molecules exert greater pressure or force than the weight of the craft. The air pressure needed to lift the hovercraft equals the weight of the craft and the passengers divided by the area. Pressure = Force / Area. It seems like pressure and area are inversely proportional, however, the larger the surface area, the greater the weight of the craft and therefore more pressure would be needed. Also the larger the area, the greater drag or resistance on the craft is created.
  26. Oh so that is probably why people take their earrings or remove any metal piece off their body before they get a MRI.
  27. Is time travelling even possible? Maybe, but to time travel a person has to be faster then light which is impossible because no one has enough energy to move faster than that speed. However, Einstein’s special theory of relativity, developed in 1905, shows that time passes at different rates for people who are moving relative to one another - although the effect only becomes large when you get close to the speed of light. If anyone has seen the TV show, the "Flash," the Flash is able to run at incredible speed. He is relatively faster when a person watches him. But in his own body he is running normally while everything else in the background is a blur. Relative to him running at a speed close to light, his perception of fast is different to a person that is much slower than the speed of light. But there may be an out to be found in general relativity, there are a possibility of wormholes – a kind of tunnel through space-time connecting otherwise very distant parts of the universe.f the “mouths” of the wormhole are moving relative to one another, then traversing the bridge between different points in space would also take a traveler to a different point in time to that in which she started. The Flash is fast enough that he creates his own wormhole where he is able to travel between worlds and time itself.
  28. That is so cool. I can't begin to imagine all of the complex computer science involved in creating something like that.
  29. I never knew that cruise ships have thrusters. I can how important they are considering how of an impulse they need to deliver in order to keep the boat going in the right direction!
  30. Quite recently Boston Dynamics made another cool looking robot that is built with two legs and runs on wheels. In order for this robot to be able to move around without falling over. The ability to not fall over is helped by inertia and the very complex computers within the robot allowing for many calculations to be made in order to put the robots weight in exactly the right spot. What is the most surprising thing about this robot is it's ability to jump completely autonomously. It is able to detect an object in front of it and make the correct calculations to jump the object and safely land on the other side. The way the robot turns and stops also shows how inertia is used, as the robot is stopping it will lean back as to counter act the inertia wanting to send the top of the robot forward. Again as the robot is turning to either side, it leans the direction it wants to go in order to not tip over. Here is a short video demonstrating all of its sensibilities.
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