# piglet&WINnie_fan42

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1. ## sound waves

Sound is produced when something vibrates.. The vibration causes the medium around it to vibrate. Vibrations in the air are called longitudinal waves, which can be heard by humans. Sound waves consist of areas of high and low pressure called compressions and rarefactions. The wavelength and the speed of the wave is determined by the pitch or frequency of the sound. Wavelength, frequency, and speed can be determined if you know the other two. The equation speed equals frequency times wavelength is the equation used to do this. Since sound travels at 331 m/s at standard temperature and pressure. Also, longer the wavelength, the lower the pitch. The height of the wave is known as the amplitude. The amplitude determines how loud a sound will be - as amplitude increases loudness increases.
2. ## the sweet spot (tennis)

When you play tennis for 20+ years you will find that a tennis racket has a sweet spot in the center of the racket. When a ball hits the sweet spot, the force transmitted to the hand is much smaller and the player is almost unaware that the impact has occurred. If the ball impacts at a point away from the sweet spot, the player will feel some jarring and vibration of the handle. The sweet spot is a small spot located in the center of the racket..shown below
3. ## sound interference

After trying to use my my versace headphones I thought I would look up how the interference from my little brother Micah's mouth altered the sound that went into my ears. I found that when two waves meet, there can be two types of interference; constructive and destructive. Constructive inteference is when two waveforms meet and are added together. The peaks add with the peaks, and the troughs add with the troughs- which creates a louder sound. Destructive interference occurs when two waves are out of phase. For example, if two waveforms that are exactly the same are added, the amplitude doubles, which makes a louder sound. But, when two opposite waveforms are added, they cancel each other out.
4. ## compressions and rarefactions with tuning forks

A vibrating tuning fork is capable of creating longitudinal waves. When the fork is hit on something the tines of the fork vibrate back and forth. This causes the tines to push on neighboring air particles. The forward motion of a tine pushes air molecules horizontally to the right and the backward retraction of the tine creates a low pressure area allowing the air particles to move back to the left. Because of the longitudinal motion of the air particles, there are regions in the air where the air particles are compressed together. This causes other regions of air particles to spread apart. The two different regions are known as compressions and rarefactions. The compressions are regions of high air pressure. While, on the other hand, rarefactions are regions of low air pressure.
5. ## Soccer Physics

Soccer is the most popular sport in the world and involves lots of physics. Just to keep it simple I will stick with newtons 1st and 2nd laws. Newtons first law states â€œany object at rest, will tend to stay at rest, and any object in motion, will tend to stay in motion unless acted on by an unbalanced force.â€ An unbalanced force can be gravity or wind. In soccer however, this unbalance force is usually the soccer playerâ€™s foot. He or she will use their muscles in the body to create a force to move their leg and kick the ball. Because the ball is at rest, it will continue to stay at rest. But once kicked, it will keep moving in a straight line without any intent of stopping. The reason the ball will stop is because of friction and Earthâ€™s gravitational pull. Newtons second law states â€œThe change in velocity with which an object moves is directly proportional to the magnitude of the force applied to the object and inversely proportional to the mass of the object.â€ This can be explained by the equation Force = mass*acceleration > F=ma. The acceleration of the ball is determined by the force applied divided by the mass of the object that is being moved. This means that if the ball has a lot of mass, it will require more force to accelerate. If the ball has little mass, it will require little force. During a soccer game, it is important to know this law because if you want the ball to be moving fast, you must apply more force. If you want the ball to move just a little bit, then just apply less or a smaller force.
6. ## Physics of a fans

In the summer it feels like your ceiling fan is cooling your room. When in fact I doesn't cool the room at all. It creates a similar affect of wind chill out side but on a much smaller scale. Ceiling fans use large angled blades that push air up or pull it down creating a small current inside your room making sweat evaporate off you skin - which makes you feel cooler. The angled blades collide with air particles in the path of spinning blade causing them to have forward momentum-downward if on the ceiling. The faster you spin the same size blade the faster the current created - making air in your room move quicker and thus making liquid evaporate quicker.
7. ## mary poppins = terrible physics

When Mary Poppins uses her umbrella to fly it is unlikely that anyone would be able to replicate this using normal wind speeds and a normal sized umbrella. Firstly you would need a force upwards that equals your weight downwards. If her umbrella is about 2 meters across and if marry weighed 50kg, using a website i found that she would need about 16.8kg per meter. You would need an updraft speed of around 15 m/s or about 29 knots. That is a big updraft - not one you would normally see outside of a thunderstorm-showing that the physics in the movie is not as real as it seemed to my 6 year old self.
8. ## Physics of dominioes

Dominoes are are actually quite powerful. Discussed on this website: http://www.insidescience.org/content/dominoes-more-powerful-you-think/924. Dominoes, once pushed, can knock over a domino 1.5 the size of the previous one. If you set up 29 dominoes- the first one being the size of a normal domino then the others following the first one gets increased in size by 1.5x the size of the previous, the last domino would be the size of the empire state building. Only a small amount of the mechanical energy is lost when friction between the falling dominoes creates heat. So most of the energy is transferred to the next making them tip over keeping most of the mechanical energy in the system.
9. ## should I run or walk in the rain

In this video https://www.youtube.com/watch?v=3MqYE2UuN24, it answers the question: is it better to walk or run in the rain. Before watching the video I decided to make some predictions. I looked around and found this website http://www.wired.com/2011/08/how-fast-is-falling-rain/ I found that rain falls anywhere between 7 to 18 mph (or 3-8 meters per second) which does not including wind-driven rain. I originally thought that the faster you moved the less wet you would be because if the rain is falling at a constant speed you are decreasing the time you are outside by moving faster. I was surprised to know that I was somewhat correct.
10. ## My Dusty Story (Cont.)

I was there guys, he actually tripped over a purse going about 1.3m/s

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12. ## Physics in Legos

I love the feeling of stepping on a Lego brick
13. ## Physics in Ice-Skating!

I never fall when I skate but I always catch people slippin
14. ## The Physics of Ripping Rubber

k bobby. I'm sure..
15. ## Physis of an Acorn

Wow your stories are super funny and very relatable to physics
16. ## The Physics of Drifting

Remember that time you almost killed pat and I in your car. I forgave you just because you can drift.
17. ## Physics of Yung Chewy (Cont.)

I like how you can calculate the final velocity using physics but ur arms are weak.

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19. ## Physics of Tsunami

http://hyperphysics.phy-astr.gsu.edu/hbase/waves/tsunami.html This article is about the physics involved in the tsunami that happened of the Chilean coast. The tsunami reached the coast of Hawaii in about 15 hour and japan in 22 hours. This tsunami started from an earthquake. The waves start from the epicenter and expand outwards. When the wave was at a depth of 7000 meters it was moving at a velocity of 943m/s. Physics played a key role in keeping people safe because they were able to calculate the time it would take for the tsunami to get to the shore so people would be able get to a safe distance before the wave hit.
20. ## Car Spoilers [Blog Post #4]

Spoilers are the wings attached to the back of a car which increase the grip between the tire and the ground. You can often find spoilers on the back of performance cars. They are used to create downforce so the back wheels get pushed into the ground when the car is moving at high speeds. When the tiers are getting pushed into the ground more friction is being created thus more grip between the tires and the ground. At an angle of about 21 degrees the ideal amount of drag and downforce is being created from the air passing over the spoiler. When air passes over a spoiler at low speeds it is unnoticable. But, at an angle of 21 degrees you would start to feel a big difference at around 75 mph and up from a car with a spoiler to one that does not.
21. ## Will's Jump [Blog Post #2]

Just like in class, we are calculate someones maximum height reached during a vertical jump by using simple math. When Will leaves the ground his vertical acceleration stays -9.81m/s^2 (air resistance neg.) throughout his entire duration in the air. I also know that will was in the air for about .64 seconds. But, when solving we cut the time in half because we only need to look at his ascent or descent. Knowing this I am able to calculate Will's maximum height while he was in the air. When will reached his peak height, he was about .502 meters above the ground.
22. ## Aerodynamics [Blog Post #3]

Aerodynamics plays a big part in car design. This is because a car that has less air resistance will use less fuel than a car with more air resistance (same engine w/ different car bodies). Furthermore, a car with a more aerodynamic body will be able to get to a higher speed than a car with a less aerodynamic body. The Top Gear video shows a car with a body that is not very aerodynamic. On the other hand, you can see that the wind passing over the Mercedes SLS AMG has a much smaller resistive force on the car. Thus allowing the car to move faster and use less fuel with this body rather than the other one.
23. ## Max's post

Hello, my name is Max and I'm a senior in high school. Since everyone else is talking about the sports they play...I will too. My mother often asks me to stop playing tennis because it is such a physical sport, but I rarely listen to her so I continue to play at a varsity level. I can't have any pets except a boring fish because my dad is allergic to the fur on cats and dogs. At the moment I work at a restaurant called Hose 22 and I usually prepare food. I'm taking physics because it was recommended to me by my counselor. But I am excited to start physics because it looks like its going to be very different from all the other science classes. I also really want to learn more about the different forces that can act on objects.
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