Many people think time travel is absolutely ludicrous, but one has to consider what kind of time travel they are referring to. To travel back in time is ludicrous, because if this were ever to become possible, there would have been discovered evidence of time travelers from the future that came to our time. Time travel according to Einstein's theory of Relativity, however, is not only plausible, but true. According to Einstein, as one increases the speed at which they travel, the rate of change of time is less for them than it is for an outside observer. Based on this idea, one can travel in time by going at incredibly high speeds. By traveling at high speeds, a person will age slower than an outside observer, showing the person traveling so quickly will have, in essence, time traveled forward. So time travel backward will, most likely, never exist, but time travel forward, if great enough speeds are attainable, is fairly simple to accomplish.
Entries in this blog
Many people understand that the third pedal on a piano allows the notes to be held out for longer by not allowing the strings to be muffled inside, but the first and second pedals are a mystery. The first pedal is also a mystery to me so I won't discuss that one, but the second pedal makes the notes played softer. There is a fair amount of physics that goes into making this happen in a piano. To reduce the sound, the strings are lightly touched so that they cannot vibrate as vigorously, but not too much so that they are cut out. But why does reducing the amount a string vibrates reduce its volume? It is not because the speed at which the string rotates is reduced, but rather because its amplitude is reduced. The amplitude of a strings vibration is directly proportional to its volume. So as the amplitude is decreased by the mechanisms in the piano, the volume that the piano plays at is decreased. If anyone does know what the first pedal does, I am interested so leave a comment.
In a show I recently stumbled upon, a man was told to walk the plank. This plank was nailed down, but considering a plank that wasn't nailed down, one could find the length at which to extend the plank off the ship so that it wouldn't tip over when a person with a known mass walked across it. To calculate this, one has to think about the torques applied to the plank. The torques applied, assuming the person is at the end of the plank and the plank has a uniform mass, is only the torque applied by the person and the plank. The torque provded by the person is calculated by the person's mass multiplied by the acceleration due to gravity multiplied by the person's distance from the position at which the plank is being pivoted. The torque provided by the plank is the plank's mass multiplied by the acceleration due to gravity and the plank's distance from the pivot to its center of mass. An equation can then be solved by knowing that if the plank doesn't rotate, its net torque is zero, and therefore the torque provided by the person is equal to the torque provided by the plank. By setting up this equation the position at which the plank should be placed can be determined.
When looking at the sport of bowling, one can easily say the velocity at which the ball is thrown and its mass are the factors in whether or not the pins fall down, but which one matters more, or do they have the same amount of importance? When looking at this question, momentum has to be focused on. The momentum of the ball as it is thrown is what causes the pins to fall down. As momentum is conserved as each pin hits another, the initial momentum of the ball is what matters most. But what is momentum? Momentum is defined by an objects mass multiplied by its velocity. Therefore, the balls mass and the velocity at which the ball is thrown have equal amounts of importance in knocking down the pins. Therefore it's best for a bowler to pick a ball that is heavy, but not so heavy that the bowler cannot throw it with a sufficient velocity.
When a skater goes into a spin, they usually start it with their arms out wide, spinning at a slow pace. Then the skater pulls their arms in and the speed at which their rotating increases and finally as the spin comes to an end, their arms extend again and they slow down. Many people understand that physics is incorporated in skating, but they don't understand how much goes into a simple spin in terms of physics. Rotational momentum is defined by the objects moment of inertia multiplied by their angular velocity. An object's moment of inertia is defined by their mass multiplied by their radius squared, multiplied by a constant determined by the shape of the object. Therefore, as a skater pulls in their arms, their radius decreases, decreasing their moment of inertia. Since rotational momentum is conserved during the skaters spin, their rotational velocity increases as their moment of inertia decreases. It is astonishing how simple something so mesmerizing can be after the physics behind it is understood.
Many people spend the winter practicing thrilling winter sports such as skiing or snowboarding, but I like to stick with simplicity. Sleding requires very limited skill to still have the thrill of gliding down a hill. There is also a lot of physics behind sleding, specifically how to turn on a sled. People seem to automatically know that they should lean to a side to turn to that side on a sled, but why? It's all about the normal force. The sled glides down the hill because of the force of gravity on the sled and the person in the sled but turning is a different story. Once a person leans to the side they are push by the snow because they have rotated the snows normal force on the sled. Initially the normal force is perpendicular to the sled but once the sled is turned, the normal force is at an angle, causing the sled and the person to be pushed to the side. This is why simply leaning to the slide one wants to turn works in sleding, and the basic concept even holds true in skiing and snowboarding.
In my limited time playing tennis for school and ping pong in my free time, I've learned how to properly return a fast serve. I would always see a quick serve coming at me and be tempted to swing hard back at it, but that would always end in the ball soaring off to either side. My coach instead told me to just hold my racket still and steady and let the ball bounce off of it. This technique has a lot of physics behind it that makes sense. Think of a ball being bounced on the floor. The floor does not swing at the ball to propel it back to your hand, rather the ball merely hits the still floor and goes back up. This can be thought of an elastic collision where all of the potential and kinetic energy of the ball is conserved causing the ball to bounce back up to one's hand. Similarly in tennis and ping pong, a fast serve met with a still racket causes the ball to go across the net with the same speed as it was served with but in a controlled manner. Therefore, even though swinging at the ball will cause its speed to increase, to get a fast AND controlled return, one should cause and elastic collision with the ball and the racket by holding the racket steady and still.
I often play pickup basketball with my brothers, the teams usually split up as me and Paul vs Nathan and Dave. Paul is garbage, however his terrible form and his "signature move" has a lot of physics involved with it. Paul believes the greatest shot is one where he dribbles along the three point arc and chucks up a shot one handed while falling backward. He believes the best way to make this shot is by aiming for the white square on the backboard. This is surprisingly not the best tactic however. Even though every coach tells their 5 year old players to aim for the magic white box, in Paul case, they shouldn't. Since Paul is moving sideways with some velocity, the ball is also moving sideways with the same velocity. Therefore, if Paul aims for the white box, he will end up missing it because the ball will not travel straight but slightly sideways due to Paul's velocity in the horizontal direction. Therefore, Paul should aim to one side of the white box so that the ball actually hits the white box and has a chance of going in. However, playing with Paul turns into an hour of pain and frustration.
Biking is one of the most electrifying activities out there. Picking up speed as you approach a jump, wondering how much air you'll get and then being launched into the air. Not many people, however, know all of the physics behind just simply going off a jump. It can be thought of in terms of kinematics by knowing the bikers initial velocity, but then one neglects how the biker obtained that initial velocity. Rather we can consider work and energy to talk about the correlation between the force of the bike, the distance the biker accelerates, their final velocity and the height they get off of the jump. Since work is equal to the bikes force multiplied by the distance the force is acting for, and since work equals the change in kinetic energy, the greater the force or the greater the distance, the greater the bikers kinetic energy. When looking at kinetic energy of the biker, we can look at linear and rotational, but for simplicity we'll just focus on linear. Since linear kinetic energy is a function of speed and mass, the speed of the biker increases, because the bikers kinetic energy increases and the bikers mass is constant. Finally, if the biker has no potential energy before the ramp, and no kinetic energy at his maximum height, we can set kinetic energy equal to potential energy, a function of height, mass and the acceleration due to gravity. Therefore, the height a biker gets is dependent on the bikers speed, but since his speed is dependent on the bikes force and distance that the force acts, the height the biker ultimately attains is dependent on the bikes force and distance that the force acts.
In a recent lab done in my physics c class, my group was experimentally determining the moment of inertia of six different objects. We set up a ramp for the objects to roll down at an angle of 3.325 degrees. We rolled the objects down the ramp, recorded the time for each object and then found each objects linear acceleration, radius, angular acceleration, mass, net torque and finally moment of inertia. When we checked our answers with our teacher they were horribly wrong, like an average of 200% error. This was because we neglected ed to include for unction in our calculations for torque.
This was a major mistake seeing as friction is the only force on the objects that provide a net torque. We went back and fixed our equation for net torque, which previously was the radius of the object multiplied by the x component of the force of gravity, to be the x component of the force of gravity subtracted by linear acceleration and the objects mass, this result was multiplied by the radius to get the net torque. Our lab then produced less massive percent errors, so my advice to you if you are doing a rotational motion lab is don't forget friction!
You may have wondered why it seems that all of your cereal clumps together in the middle of the bowl, even when you only have a few bits left to eat. The fact that cereal accumulates toward the center is due to something scientists have called "The Cheerios Effect." In 2005, the effect was mathematically proven. The surface tension between the milk and the bowl causes the milks surface to cave in slightly toward the middle of the bowl. Similar to the cohesive and adhesive properties of water, these properties in milk cause a concave surface of the milk. Clearly once one understands that the surface of the milk is caved toward the middle of the bowl, it is clear that there is a component of the force of gravity pushing the cheerios together into the middle of the milk's surface as the friction between the milk and the cheerio isn't enough to counteract the component of the force of gravity.
My family and I were making bread the other night and my mother had to teach us how a flat piece of dough could turn into a delicious, golden brown loaf. All she knew was that heat made the dough rise, but there is so much more physics involved in making bread rise. In terms of energy, as heat from the oven goes into the dough, the heat energy is turned into mechanical energy in the molecules of the bread, mostly in the form of kinetic energy. This conversion from heat energy to kinetic energy causes the molecules to increase their speed and begin colliding with one another. As the rate of collision's increase, the molecules "look" for more room as to not collide with so many other molecules. This causes the bread to rise as the molecules push outward to avoid hitting other molecules. The conversion of energy combined with molecular movement causes the dense dough to become a fluffy loaf of bread.
My sister Abby loves to make pancakes for breakfast. She makes three small pancakes at a time using one pan. How does this cook all of the pancakes evenly? This is where physics comes into the equation. The flame is concentrated in the middle of the pan, so wouldn't that be the only place where the pancakes would be able to be cooked? One would assume so, but due to energy and particle movement, the entire pan is able to cook a pancake, even though the flame is not directly under that spot. The flame heats up the molecules in the pan directly above it, causing the heat energy to be converted into kinetic energy. As the molecules then move rapidly, bouncing off one another, the collisions with other molecules in the pan transfer energy from one molecule to another, transferring energy across the whole pan. The kinetic energy in each of the molecules and collisions cause the entire pan to heat up. This is why it is possible to make three pancakes by using just one pan.
Fall is by far the best season. It's not too hot, not too cold and the leaves falling all around create beautiful views any way you turn. Physics is also all around during fall. To pick one example, falling leaves illustrate many principles of physics. One could pretend air resistance doesn't exist and see a leaf fall 9.8 m/s^2 in a straight line to the ground, but that would take away from the beauty of the leaf falling. One would have to include air resistance, measured by either bv or cv^2, where b and c are constants and v represents velocity of the leaf. Even the inclusion of air resistance, however, wouldn't totally explain the nature of the leaf falling. It would describe the leaf speeding up as it falls, eventually reaching a terminal velocity until it stops on the ground. The irregular shape of the leaf is what needs to be taken into account to truly define the nature of the falling leaf with physics. The irregular shape is what makes the leaf move side to side, accelerating at different rate throughout its fall. If we were to consider a ball falling, air resistance would be easy to calculate, but due to the irregularity of the leaf, the nature of its fall is difficult to explain in terms of physics. It is amazing how complex the physics is behind an object as simple as a falling leaf.
One of the most creative sounds in music is when a composer is able to resolve a chord. The chord starts out sounding as though the pitches are fighting each other, this is called dissonance. The listener hates this sound, but it makes the resolved pitches sound even better. To resolve the chord, the dissonance is ended by balancing out the wavelengths of the pitches. This is done by changing the notes in the chord such that their frequencies create regular harmonies such as a third and a fifth. The physics behind resolving a chord is extensive, but at the same time straight forward. The frequencies of the pitches that create dissonance are so close together, almost the same, that the waves created make a sound that could be compared to the notes fighting with each other, and to some extent this is true. The pitches don't want each other to change frequency, but the listener desperately does. This is the reason why resonance sounds so good. Once the pitches stop "fighting," once the pitches frequencies are in pattern with each other, the conventional chord sounds a thousand times better being played right after dissonance.
In the greatest comedic film ever created, Homer Simpson attempts to ride a motorcycle around the inside of a dome. He accomplishes this feat in order to throw a bomb out of the inside of the dome. Not only is this the coolest stunt ever pulled in any movie in the history of film, the physics behind this accomplishment is elegant. In previous attempts when Homer failed, he drove too slowly and so he would fall when he got to the top of the dome. Lisa knew about physics, however, and told Homer to speed up when he got to the top. When he did this he was able to get to the top of the dome without falling off. He was able to do this because his increase in speed increased his momentum. Since momentum, p, equals mass multiplied by velocity, Homer's momentum would increase when he sped up toward the top of the dome. Therefore, he was able to clear the dome because the force of gravity opposing him stayed the same and his momentum increased, causing him to go all the way to the top of the dome without falling, after, of course, multiple failed efforts.
By far the coolest thing you could do with a car is drift, but most people don't know the specifics behind drifting and how much physics is embedded in drifting. When someone drifts, they turn the car abruptly and then turn the wheel in the opposite direction they want to turn. This action, however, however seems counterproductive. Why would turning the opposite direction move the car in the intended direction? To answer this question, you need to know the nature of friction and Newton's laws. When the car begins to move sideways, the only force acting on the car is the force of friction from the pavement on the wheels of the car. This force makes the car slow down, since net force is equal to mass x acceleration, and the force of friction is the only force acting on the car. But why would friction change the direction of the car? The answer to this lies in the concept of centripetal forces. Centripetal forces are forces that are center seeking and cause an object to move in a circle around a point. Therefore, when the wheel is turned in one direction, this causes the force of friction applied on the wheels of the car to become a centripetal force, causing the car to move in the intended direction rather than the direction that the wheel is turned in. All of this considered, drifting in a grass field is definitely a thrilling activity, even if you don't know all the physics behind the movement of your car.
Physics plays a massive part in music, whether instrumental or vocal, but physicists and musicians rarely realize the depth of the relationship between the two. As a tubist and a physics student, I find how closely intertwined physics and music are to be intriguing. Most people know that the tuba is an incredibly low instrument, second only to the contrabass saxophone, which is rarely found in a concert band anyway, but when asked why it is, the most common answer is because its big. This answer isn't totally incorrect, but there is so much more to be considered in terms of the physics that makes the length of the tubas tubing contribute to its incredibly low sound.
The low sound of a tuba can be attributed to the low frequency of sound waves that the tuba produces, but what is the real reason for the low frequency produced? The answer to this is found in the size of the instrument. The tuba is made up of about 16 feet of tubing. The length of the instrument causes the wave length of the sound it produces to be very long. Therefore, because frequency equals the speed of the wave divided by the wavelength, a greater wavelength will yield a lower frequency. The physics behind music is something astounding yet often glossed over.
In a lab recently conducted by the Physics C class, Mr. Fullerton required the class to place a textbook at a location where they predicted a ball launched by a projectile would fall. The class got one test launch to observe the behavior of the projectile and then the angle that the projectile was launched at was changed and the location of the ball when it lands had to be predicted. The class failed to calculate the final location of the ball due to improper calculations, specifically not representing certain vectors with their proper direction. In the initial lab, the distance in the y direction was thought to be positive instead of negative. This threw off our calculations for the initial velocity of the ball in the y direction and therefore made our initial velocity, the combination of the x and y components of the velocity, incorrect. Since our initial velocity was incorrectly calculated based on data for the first trial, we did not have the proper initial velocity for the projectile when the angle it was launched at changed, causing us to have the wrong final answer to where the ball would land when launched from the new angle.
After redoing the problem and realizing what we did wrong, I came to an answer of 199.42 cm in the x direction for the distance the ball would travel in the x direction before hitting the ground. By changing the y direction value for the first trial calculation to a negative number, this corrected the initial velocity in the y direction and thereby corrected the overall initial velocity. Then when calculating the value the ball would travel in the x direction for the second trial, checking over that all vectors had the correct associated directions, the time was first calculated by utilizing the y plane using the equation dy = vt + 1/2at^2. The time found for how long the ball was in the air was .427s. The time was then used in the x plane to find the distance using the equation dx = vt. This equation yielded the final answer of 199.42 cm as the distance the ball traveled in the x direction.
I grew up in a large family with 6 siblings. As a triplet and having four older siblings, I have never really been on my own in any activity. My family is extremely close and most of the activities that I do outside of school, such as soccer, singing, playing the tuba, and acting, I do with at least one of my siblings. I am a captain on the varsity soccer team in high school and soccer is one of my greatest passions. I am studying physics this year because I loved what I learned last year and I am intrigued to find out what else there is to be discovered in physics. I am super excited for physics this year as well as calculus and economics. I'm also enthusiastic about my senior year, but at the same time extremely anxious about choosing colleges to apply to, thinking about ACT and SAT scores and having all of my homework to do on top of that. Even though it will be a lot of work, I am excited for what this year will teach me.