The gold foil experiment is the famous experiment conducted by Ernest Rutherford that we all learned about in chemistry class. This experiment proved that atoms are made up of mostly empty space. In fact 99.9999% of an atom was proven in this experiment to be empty space. Lets say we could eliminate all that empty space by condensing the parts of an atom together. How much weight could we fit in a small space such as a single teaspoon? Over a billion tons!
This idea is common when studying astronomy. At the end of a stars life, it collapses and explodes in a supernova explosion. The remaining mass that the supernova leaves over is so dense that the star begins to collapse in on itself. As a result of this, electrons fall into the nucleus and smash into protons becoming neutrons; hence the name neutron star.
This animation shows a star going through a supernova explosion. The accuracy of this animation is highly questionable but it certainly looks cool.
The Doppler effect occurs in everyday life more often than you may think. It is the change in frequency or wavelength of a wave relative to a moving observer.
In this animation a car has sound waves that it is emitting. As the car starts to move the wavelength of the wave becomes smaller on the side of the car that it is moving toward and larger on the side that it is moving away from. An observer on the left side of this car would hear it gradually become higher pitched. An observer on the right side of the car would hear it gradually become lower in pitch.
The Doppler effect is true for light waves as well. This is wear the terms red-shift and blue-shift come from. Blue light has a higher frequency than red light; therefore if an object appears to be becoming more blue that means it is moving toward you. If an object appears to be turning more red than it is moving away from you. This is only noticeable on very large scales like when observing space. Because of the Doppler effect, scientists have determined that our universe is expanding since most objects in space are red-shifted relative to earth.
The first telescope to be invented was a refracting telescope. A refracting telescope works by using converging lens to collect light. A refracting telescope has a convex lens that bends the parallel light that is coming into it to a focal point. That focal point is where an image is formed of what is being observed. At that point is the eyepiece that you look through to see the focused image. This diagram shows the inside of a refracting telescope.
A reflecting telescope was invented after that refracting telescope by Isaac Newton. A reflecting telescope works by collecting light and reflecting it off of a concave mirror. The light that is reflected comes to a focus point where a flat angled mirror reflects that light up toward an eyepiece where the viewer sees the image. This diagram shows the inside a reflecting telescope.
Our latest unit in Physics was learning about magnetism. A magnetic field occurs when charged particles are moving. According to greek legend magnetism was discovered by a Shepard in a field as he suddenly felt a force of attraction coming from the ground as he wore shoes with iron on the bottom. The substance he found later became known as magnetite, after the place it was found, Magnesia. Another common magnetic substance that was well known was lodestone. This was used in ancient China by the first emperor to protect his palace. Huge blocks of lodestone were placed outside the entrance. This was meant to attract soldiers in armor so they were prevented from entering the village. In ancient Egypt magnets were used for entertainment by doing (non) magic tricks. They would place objects above a magnet so that they would repel so the object would seem to be floating in mid-air.
It wasn't until the 1500's that magnetism was scientifically investigated by William Gilbert who discovered that the earth itself is a magnet with a magnetic north pole and south pole. Not too much later came Friedrich Gauss and Charles Coloumb, where our understanding of magnetism became less of a mystery. In 1861 James Clerk Maxwell used equations to relate magnetism and electricity.
Major league baseball opened up the season this week and there were some exciting stats and physics involved in the 11 games that were played on Thursday the 29th. Here are some of the great physics highlights of opening day.
Giancarlo Stanton hit 2 home runs on his yankee debut. One of his home runs leads the league, so far, in exit velocity off the bat: 117.4 mph. With a launch angle of 19.8 degrees, its projected distance traveled is 426 feet.
Jordan Hicks of the St. Lous Cardinals has the fastest pitch of opening day at 101.6 mph. At this speed, Hicks produced a spin rate of 2,233 rpm. While this ball had a great amount of kinetic energy, it also had a large amount of rotational kinetic energy as well. The highest spin rate of 2,649 rpm was thrown with a 99.2 mph four-seam fastball by Aroldis Chapman.
The farthest home run of the season so far is by Matt Adams of the Washington Nationals. He hit the ball 460 feet with a velocity of 109.3 mph and launch angle of 28.6 degrees.
Physics is always relevant in baseball. Throughout the 2018 season there will be a lot more exciting stats while it is only the beginning.
Want to make brushing your teeth even easier than it already is? Try using an electric toothbrush that uses an electric motor to rotate the brush back and forth to scrub your teeth better than ever. How does it work? On all the electric toothbrushes there is a battery at the bottom. This is used for a source of voltage which creates a current. As the current goes through the circuit, it reaches a point where it experiences a magnetic field. This creates a force upward on the circuit causing a net torque in the clockwise direction as shown in the diagram.
As the circuit rotates 180 degrees, the direction of the current switches; therefore, the direction of the force switches, so it turns around the rotation. This back and forth motion gets transferred to the brush which is why it is so effective in making teeth super clean and white.
Anybody who has ever taken a physics class knows that math plays a very essential role in solving problems that explain the laws of the universe. The question is: has math always existed and waits for us to discover it, or is math our own invented logic? There are many mathematical phenomena that are mysteriously found to come up in nature such as the Fibonacci sequence, and the numbers e and pi, that would be evidence of math being a preexisting language of the universe that we are continuing to discover. There are also some people that would say numbers are just a way for our conscious to understand how things work. Aliens might not know what math is but still have there own unique way that they understand the universe without using numbers in any way what so ever. The argument can go both ways but one thing is for certain: for humans, math has never failed us in our journey in studying the universe, so whether it is made up or not, it works!!
Water and ice molecules on earth have a distinct molecular structure that gives it the properties that it has; however, under different surrounding pressures, the molecular structure can change, resulting in the formation of superionic water. Superionic water differs from the ice/water you and I know so well. "Regular" ice has molecules that form a V shape with two hydrogen atoms and one oxygen atom. As pressure increases, these atoms get squeezed into different shapes. A property that superionic ice has is that it is a conductor of electricity; however, unlike most conductors, the current is carried by positively charged ions instead of negatively charged electrons.
This substance was just a theoretical idea until recently when the University of Rochester's OMEGA laser tested the theory and was successful in creating superionic ice. They knew this was a success because the molecules were able to conduct electricity. Due to the opaque color of the molecules when electricity was ran through it, it was determined that it was, in fact superionic. If it had a shiny look to it, the researchers would have known that it couldn't of been superinoinc because that would mean that negative electrons were carrying the current.
The pressures that were applied to the ice by the laser were almost 2 million times the atmospheric pressure of earth. This is the amount of pressure that planets Neptune and Uranus have.
Every massive object in space has an escape velocity. Escape velocity is the minimum velocity an object must have in order to escape the gravitational strength of a particular planet or any large body in space. The earths escape velocity is about 11.2 km/s. This means that an object must travel 11.2 km/s to escape its orbit around the earth. Reaching this velocity is a very big challenge when dealing with space travel. The more mass a body has, the more gravitational attraction it has; therefore, the escape velocity becomes faster.
A black hole's escape velocity is so high that nothing can escape its gravitational pull; not even light. That is why its call a "black" hole: there is no light coming out of it so you can't see in it. A black holes escape velocity must be greater than 300,000 km/s (the speed of light). How can in object have this must mass to generate this much gravitation? When a star reaches the end of its life, some of them collapse all the way down to a single point, maintaining it's mass. This means that it becomes infinitely dense. Our sun does not have the potential to eventually become a black hole because it is too small. Stars that become black holes are 20 times the mass of the sun.
Super Bowl LII is nearly 2 hours away. The Patriots and the Eagles are both great teams with lots of talent. Not only will I be watching the game, but the physics of the game as well, being a physics student. Some things worth taking note of are the kinematics of kicking a field goal, the forces that are felt while getting tackled, the kinematics of deep passes made by Tom Brady and/or Nick Foles, among many others.
The minimum height needed to complete a successful field goal is 10 feet. A typical field goal is kicked anywhere from 30 - 40 yards away from the goal post. Depending on how windy it is will determine the correct angle and velocity at which the ball should be kicked.
Lineman can weigh up to 300 pounds, so running into them is not fun for running backs. When the defensive lineman start to charge over the line of scrimmage they posses a tremendous amount of momentum. While running backs also have the ability to reach a great amount of momentum due to there ability to reach very high speeds, they don't have the mass to match the linemen. Also when running backs come in contact with lineman it is usually at or behind the line of scrimmage, not allowing them to pick up a high speed to match the momentum of the large linemen.
There is more than just throwing a ball up in the air really far when quarterbacks toss those amazing 60- 70 yard completions near the out of bounds line. Quarterbacks have to time it perfectly so the ball reaches the target at the same time the wide receiver arrives at the point where the catch is made. A successful completion all depends on the speed of the wide receiver and the trajectory at which the quarterback throws the ball into the air.
Hopefully Super Bowl LII brings us lots of cool physics to observe.
The many worlds theory suggests that there are an infinite number of universes that exist outside of our own. This theory was developed by physicists studying quantum particles. In quantum physics some things can have properties of either particles or waves and there is no way to determine which one. This influenced the many world theory because in quantum mechanics things have a wave-particle duel nature, so each fate of a particle is carried out, but just in different universes.
According to this theory you are not the only you. You are living in an infinite amount of universes, each with different possibilities of you. All the possible alternatives that ever existed in history exist in a different world. Anything that could have possibly occurred in our past actually did happen in a parallel universe.
Many scientist refer to these universes as giant bubbles floating around in space as shown below.
Light from the sun takes approximately 8 minutes to reach us on earth; however, that does not mean that those particular photons are 8 minutes old. The suns light is produced in the center of the sun when massive amounts of energy is released. The sun has a radius of 696,000 km. The distance between the edge of the sun and the earth is 149.6 million km. From this information you would come to the conclusion that it takes less time for a photon to reach the outer surface of the sun than it would to reach the earth. The truth is that it actually takes much longer for a photon to travel from the center of the sun the the edge. This is because as a photon is released it travels through the sun with a lot of stops along the way. A photon can only travel a certain distance inside the sun without being absorbed and released by an atom. As a result, it can take up to millions of years to finally reach the surface of the sun. A cool way to think about this is that the light from the sun can potentially be produced millions of years plus 8 minutes ago.
Usain Bolt: the fastest man alive is 6'5" and 207 pounds. Being this large is rare for a sprinter because 207 pounds takes a lot of work to accelerate. To make up for this disadvantage he sprints quite differently than others.
His average stride is 2.44 meters long. This means that in a 100 meter race he only takes 41 strides. That saves a lot of time because the more times that you come in contact with the ground, the more time it takes to complete the race. In the World Championship in Berlin, Bolt's closest competitor made 2.22 meter strides, resulting in about 45 steps through the 100 m race. Bolt finished in 9.58 seconds(the world record), with an average speed of 10.44 m/s and maximum speed of 12.42 m/s.
Long strides is not the only thing Usain Bolt does differently to improve his speed. Every time bolts feet touch the ground he rotates his body about 20 degrees from the vertical forward as he pushes off from the ground. Being so tall he has a lot of gravitational torque when he leans forward. He uses this torque to his advantage by allowing his body to free fall forward.
Take a look at Bolt's record breaking race in the world championship in Berlin.
Cristiano Ronaldo is one of the best soccer players in the world. He is known for jumping extremely high to score headers. Headers are goals scored by using your head to hit the ball into the goal. This is a very useful skill in soccer because if you can jump higher than all the defenders than you can hit the ball without the defender getting in your way. Just how high does he jump? In a sports science analysis, Ronaldo jumped in mid air with his hands on his hips. The result was a height of 44 cm in the air. This is about average for a soccer player, so this would not be successful most of the time when going for headers. A second test had him jump as high as he can with a running start. The result was a staggering 78 cm. That is higher than the average NBA player! In order the accomplish this he jumps off of the ground with a force of 50 N.
In one of his most famous goals, against Manchester united, Ronaldo's head reached a height of 263 cm which is equivalent to 8 ft 6 in.
For centuries scientists have studied the cause of gravity. Even though there have been theories that have proposed reasons for gravity, we still don't know for sure what exactly causes it. Isaac Newton developed the idea of gravity in the 17th century. He said that it was just a force of attraction that all objects naturally had toward each other. It wasn't until the early 1900's when Albert Einstein came up with his theory of relativity that explained the reason why objects attract each other.
The theory says that massive objects warp space-time which causes these objects to fall toward each other. What is space-time? Space-time is the combination of space and time into one thing. This sounds really strange but every time it has been tested, it has never failed;however, that's not to say that it is completely proven. One way you can prove this is if you go to the top of an extremely high building, time actually speeds up. This is because the further you are from the earth, the less warped time is. That goes for space as well.
There is much more to this theory. This is just a very brief explanation of how Albert Einstein tackled the idea of gravity.
Bowling is one of my favorite activities to do during the winter time. I've tested a lot of different ways to throw, trying to come up with the most effective and consistent way to bowl strikes. I found that hitting the front pin straight on does not work every time because when it hits the front pin right down the middle, the outside pins often wont get touched leaving you with a pretty bad split.
The best thing to do is to hit the front pin but from an angle. What I mean by this is that when the ball comes in contact with the pin, it should strike it from the side of the pin. This causes more pins to fall because when the pin falls at an angle instead of straight back, the bowling ball does not follow the front pin after contact. The front pin will fall to the left causing the left side pins to fall, and the ball will move slightly to the right causing the right side pins to fall. This is due to conservation of momentum.
To accomplish this I put spin on the ball to make it curve into the side of the front pin. At the beginning of the balls path it slides on the hardwood, but after a while the friction of the floor will cause the ball to only move through rotation. If the spin is in the direction that is perpendicular to its original velocity then it will curve inside.
Gym class is filled with exciting games every year. One of my favorites is badminton. One of the amazing things about badminton is that is uses a shuttlecock, or birdie, that is volleyed back and forth over the net. What's amazing about the shuttlecock is that it always flips on impact so it flies with the cork facing forward for the opposing team to hit it back. What makes it flip?
The mass of the shuttlecock is not evenly distributed. Most of the mass is in the cork part of it. The shuttlecock also holds a shape that is similar to cone. This causes more air resistance to the back, or feather, part of the shuttlecock. As a result the cork is moving at a higher speed on impact and moves in front of the feathered part.
From this series of photographs you can see that when the shuttlecock is hit it is initially facing the racket, but immediately starts to rotate. As the projectile moves along, the shuttlecock completely changes direction for the opponent to hit it right back.
Car wheels have treading on the outside of each tire to increase friction between the car and the ground. Unfortunately, if the treading is worn out during the winter time the effectiveness is limited. Due to a lack of friction between the ground and the tire, and Newton's first law of motion, the car slides on the ice.
The reason that the treading prevents slipping in the muddy and snowy conditions is because of the grooves on the wheel where the mud/snow can get into. The muddier or snowier it is, the wider and deeper the treads should be. As the wheel turns the grooves dig into the soft material of snow or mud, allowing the wheel to rotate with friction to cause the entire car to move.
Without the treads the car wheel would still rotate from the torque applied to the wheel from the gas of the car, but it would not move forward because there would be no friction between the car and the ground to cause the wheel to roll.
When there is no snow the chances of slipping are less because pavement has a higher coefficient of friction than ice and snow.
Our last unit in AP physics c was rotational motion. In this unit we learned about rotational kinematics, dynamics and momentum. Rotational kinematic is very similar to translational kinematics because the same kinematic equations are used. The difference is that instead of displacement roation has the change in the angle. Instead of translational velocity and acceleration, rotational motion is calculated with angular velocity and acceleration.
As far as dynamics go, rotational motion has a very significant concept that separates it from translational motion. It's moment of inertia. Moment of inertia is the measure of an objects abilty to resist rotational motion. It could be compared to inertial mass or just mass. The other importance to rotational dynamics is the concept of torque which is a force that causes rotation mesured in Newton*meters. Torque is equal to the moment of inertia of the rotating object times its angular acceleration. Torque is also equal to the cross product of force and the distance from the axis of rotation that force is applied. Rotational dynamics is important for solving many different problems involving rotation.
Rotational or angular momentum is the measure of how difficult it is to stop a rotating object. It can be calculated using the equation L = moment of inertia * angular velocity. Angular momentum is also equal to the cross product of the objects radius and its translational momentum. It is important to know that angular momentum is always conserved, so in a closed system the intitial angular momentum is equal to the final angular momentum.
Rotation is a very important topic because it is so useful in the world of science and engineering because not everything moves in linear motion. For instance our solar system can be studied using rotation since our planets move in rotational paths.
The Engineering design process is a series of steps that engineers go through to create a product of some sort. The process can be very repetitive at times while going through a process of trial and error. The lab that we did in class demonstrated the engineering design process. We were given two paper plates, six pennies, a pencil, and tape to create a spinning top. First we came up with an idea that we thought might work so we constructed a top that had a pencil through the center of a plate with six penny's evenly spaced around the plate but not to the edge. The plate was at about the center of the pencil. This failed because the plate was not stable enough on the pencil so we added the other plate to the bottom of the first plate to stabilize it a little more. We also lowered the location of the plate to be more toward the bottom of the pencil. This would decrease the wobbling because there would be less torque on the pencil if there is a smaller distance since Torque is the cross product of F * r. These two adjustments improved the top but it still was not spinning perfectly. Something that would have made it spin a lot better would be to shorten the length of the pencil. This would have gotten rid of the weight at the top of the pencil to decrease the net torque even more.
Moment of inertia was a big part of this lab because moment of inertia is an object's resistance to rotational acceleration. An object with the least possible moment of inertia would be the most successful.
Angular momentum was also a very important part of this lab because angular momentum describes how difficult it is to stop a rotating object. Therefore, an object with the greatest angular momentum would be very successful in this lab because it would take a lot of torque to change it.
Micheal Jordan didn't get the nickname "Air Jordan" for nothing. He is known for his ability to jump really high in order to perform epic slam dunks. How does he do this?
Micheal Jordan stands 1.98 m tall and has a wingspan of 2.13 m. A basketball hoop is 3.05 m high; therefore, he has to jump about .16 m above the ground for his hand to reach the rim. Jordan is most famous for his dunk from the foul line which is 4.57 m from the basket. In order for him to successfully complete this projectile, he must jump with an initial velocity of 25.31 m/s from the ground; 1.77 m/s in the vertical direction and 25.25 m/s in the horizontal direction.
In order to produce this velocity he must push of from the floor with a force of 1454 N if he pushes off of the ground for .2 seconds.
What makes us move? Well that's obvious. It's our feet, but how exactly does that happen. The answer is newtons third law of motion: when a force is applied to one object, that object automatically applies that same force back.
When your foot presses on the surface of the earth at an angle, the earth pushes back on your foot with the same force causing your body to accelerate forward. You might say, well then why does the earth not accelerate. That's because the earth is so big compared to your body that the force that you push on the earth with is practically nothing.
You can also tie this to conservation of momentum. If you and the earth both start at rest and a force is applied to accelerate your body, the earth body system's momentum is conserved.
The last unit we studied in AP Physics C was Work, Energy and Power. First we reviewed the concept of work and how it equal to force*displacement. In a calculus based physics class however Work is also equal to the integral of force with respect to displacement. This means that the area under a Force vs Displacement graph is equivalent to the work done on the object. We also learned about Hooke's law and how it describes the relationship between the force of a spring and displacement. The slope of a graph of force vs displacement represents the opposite of the spring constant (k) of the spring. From this the equation Fs = -kx was determined. Then we analyzed the work energy theorem which shows that work is equal to the change in kinetic energy.
Kinetic energy is the energy of an object that is moving. Potential energy is stored energy that an object has the potential to use. In a closed system energy is conserved. The total energy of a system is equal to the potential energy plus the kinetic energy.
Power is a measure of the rate at which work is done, therefore power equals Work/time. From this we can also conclude that power is also equal to force*velocity. This unit will be helpful in many ways. It is an alternative to many kinematic problems and will also be helpful in other topics as well.
The Hubble Space Telescope is a large telescope that was launched into space in 1990 and has been used to see images that were, before Hubble, too far to see. Just recently, on October 20th, Hubble captured an image of a twisted cosmic knot in the constellation cancer as shown in the image below. This is 250 million light years away. A cosmic knot is what occurs when two galaxies collide to form a new galaxy. This galaxy, NGC 2623, stretches approximately 50000 light years from end to end. When galaxies merge, star clusters begin to form which is shown by the specks of bright blue that exist throughout the twisted cosmic knot. These newly formed clusters are blue because the blue stars inside the cluster are much hotter than the other stars. As time goes on the clusters will change to red because the blue, hotter stars will die out faster. Hubble has been extremely useful in the world of astronomy for discoveries like NGC 2623 and many others. Its groundbreaking technology has helped us to significantly improve our understanding of the universe.
As I was scrolling through Instagram, I came across a post by Nasa that said today, October 14th, 2017, is the 70th anniversary of supersonic flight. Supersonic flight is when something is traveling faster than the speed of sound, which is 343 m/s. Of course for the past 70 years this has only been done by noncommercial planes. Well, Nasa is currently working on making supersonic flight a reality for commercial planes. That would mean that you can travel from New York to Los Angeles in 2 hours. Now it takes over 6 hours. Nasa has been researching shock waves, cruise efficiency, and the effect of sonic booms on the environment. Sonic booms are loud boom sounds caused by the waves of sound. It occurs when an object travels at supersonic speed. If Nasa is able to make this a reality in will revolutionize modern travel.
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