Top 10 most useful concepts of Physics!

The Top ten most useful concepts of physics!
 1. The first most useful concept of physics would be Newton’s first law. Newton’s first law states that an object in motion will stay in motion or an object at rest will stay at rest unless a force causes it to change. This is also known as the law of inertia. This concept is important regarding car safety. Cars are now designed based on this law in the case of an accident. Manufactures look at the law of inertia and design airbags, seatbelts, and headrests to protect us from getting injured. If a car is at rest at a stoplight, everything in the car is at rest as well. If a car were to rear end it, the car would move forward, but everything in the car would want to stay where it is. For example, our heads, if there were no headrests that would force out heads into motion along with the car, our heads would snap off. Because of Newton’s first law, scientists know this and are able to prevent that. Newton’s first law is extremely useful in that it helps save lives by providing scientists the knowledge to prevent certain fatal injuries.

 2. Acceleration is an extremely useful concept of physics. In fact, racecar drivers to win races use acceleration. A racecar driver wins a race by driving a set distance in the shortest amount of time going the fastest highest velocity. The common person may think that a racecar driver wins a race just by driving fast, however, a racecar driver wins not just because of his speed, but because of how fast he is speeding up. This is the physics concept of acceleration. a. Acceleration = change in velocity / time. While racecar drivers measure their speed in miles per hour, in the world of physics, we measure speed in meters per second. In order for a racecar driver to win a race the physics concept of acceleration is vital to know.


 3. Another useful concept would be objects falling through air. The army uses this concept to drop supplies from airplanes to specific spots. Because of physics we can know how long and how far something will fall based on how high it is dropped from, what speed it is dropped at, and how great the air resistance is. This concept is extremely useful for the army because they are able to make precise drops of soldiers, supplies, and bombs with this knowledge.


 4. Centripetal Force! Lacrosse and roller coasters. Two very popular things in America are lacrosse and roller coasters. But what do these two things have in common? They both rely on the physical concept of centrifugal force. When an object is inside of something experiencing centripetal force, (any force directed toward a fixed center) that object is experiencing centrifugal force, an apparent outward force. It is helpful to know that Centrifugal means “center-fleeing”. For example, when you put an object in a can and spin that can around by a string, you will find that the object will remain in the can at all times. So what does this have to do with lacrosse and roller coasters? Well, lacrosse uses centrifugal force to keep the ball in the net pocket of the lacrosse stick. In order to do this, lacrosse plays move their stick in a back and forth motion called cradling. Cradling causes a centripetal force sensation causing the ball to experience centrifugal force and stay in the net of the lacrosse stick. Similarly, roller coasters rely on centrifugal force to keep people in their seats. For example, when a roller coaster goes around a loop, the people on the roller coaster experience a centrifugal force and are rooted in their seat throughout the loop. Centrifugal force is a key factor in having fun, it allows us to play sports as well as allows us to enjoy ourselves on roller coasters in amusement parks!

 5. Simple Machines, I.E. Ramps A ramp is a simple machine that makes things easier for us. Because of physics concepts, we know that the work we put into a ramp = the amount of work we get out of it (work = force X distance). The main principle that allows us to know this is the conservation of energy. The law of conservation of energy states that: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Because we know that the work input and output are going to equal each other we know that the product of the input force and distance must equal the output force and distance. However, the input force does not need to equal the output force, just the product of the force along with the distance. (force X distance) input = (force X distance) output. Knowing this, a ramp allows us to use less force by working over a greater distance. (f X D) = (F X d)! For example: If you had a 40kg box and needed to lift it 3 ft, you could grab a 4ft long board and slide the box up it. Lifting the box would be 120 joules of work, and so would sliding it, however with the increased distance you would be required to exert less force in order to get it to the same point that lifting it would. A ramp is only one example of a simple machine designed to make out lives easier.


 6. One very useful concept of physics is rotational inertia. Rotational inertia is the property of an object to resist changes in its rotational state of motion. For example, a meter stick with a weight taped to the top is going to fall down slower then a meter stick without the weight. The stick with the weight was resisting the change more then the meter stick without the weight. So how is this useful? Baseball players appreciate this concept because with this knowledge, they know that it is easier to swing a shorter baseball bat then it is to swing a longer one. Being able to swing the bat faster allows players to hit the ball harder and overall improve their athletic performance. Similarly, rotational inertia is helpful for bikers as well. Bike wheels with a low rotational inertia are going to spin faster then opposed to larger ones. So a biker would want to get wheels with less mass on the circumference in order to bike faster and win. Along with bikers and baseball players, rotational inertia is important for runners. Runners with long legs are able to go slower with a larger stride, but runners with shorter legs are able to move them quicker but with smaller strides. The whole reason that runners bend their legs is because of rotational inertia. Imagine running with your legs straight! Physics concepts, as you can see, are very much so used in sports!


 7. One vital concept within physics is the knowledge of capacitors. Because of capacitors we have defibrillator and are able to save lives. When a person dies, their heart stops. Scientists have discovered that sending a charge through a stopped heart can sometimes restart it. In order to do this doctors use a machine called a defibrillator. A defibrillator basically builds up a large amount of charge in an incomplete circuit. When the two defibrillator paddles touch the body the circuit is completed and a charge is sent through the body, hopefully restarting their heart. This is the concept in a capacitor, which also causes the flash on cameras. In a camera there are two plates and there is a large amount of opposite charges built up on each plate. The circuit between the two plates is completed for a split second and a flash of light is released. Because of physics we are able to save lives and take good pictures!


 8. Current, -> light bulbs Because of the physics concept of current we now have the ability to light up light bulbs. Light bulbs are lit when current is flowing through its filament. Current only flows when there is an electric potential difference. For example, in a battery, one side may have a certain voltage, but in order for the current to flow, the other side must have a different voltage. In order for a current to flow up into a light bulb a circuit must be completed. This means that a conductor needs to make a full loop so that the current can flow through it. A conductor is something that allows current to flow through it. In the context of light bulbs there will always be a metal wire of some sort that conducts the current. Due to the physics concept of current we can light up light bulbs and have light inside of our homes!


 9. magnetism, compasses, used to find our way
 An extremely important use of physics would be compasses. With compasses we know which direction is north, south, east, and west. With this information we are able to find our way around with a good sense of direction and are able to locate things. A compass is just a free piece of metal that aligns with the Earth’s magnetic field. The earth has a magnetic field flowing through it from south to north. The flow comes out and around the earth back into the south side only to flow north again. Our geometric North is the magnetic south and vise versa. This is because on the surface of the earth we pick up the direction of the magnetic field as the south is flowing back up in order to re enter the earth and continue to flow to the north. Because of this magnetic concept, we are able to write maps, find our way when we are lost, and have a good sense of direction.

 10. Newton’s second law of motion, skydiving
 Skydiving is a sport where people fall out of a plane and float back to the ground by a parachute. Thanks to physics this entire sport is possible. Newton’s second law of motion states that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. Mathematically this looks like: Acceleration ~ net force / mass. Skydivers are falling through air. For this there is a net force acting up on the person while gravity is still pulling them down. If you subtract these two quantities you come up with the net force. Take this number and divide it by the mass of the skydiver and you have his rate of acceleration. Because the diver is falling through air he will not exceed a certain speed, eventually he will reach terminal velocity. However, at some point the skydiver will open up his parachute. Doing this increases his surface area and therefore he increases the amount of air resistance on him. This is going to slow him down, eventually with his deployed parachute he will reach a terminal velocity at a speed that allows him to safely land on the ground.

Unit 7 Reflection!

This unit in physics we studied a lot of things relating to using motors, generators, and magnetism. We began with magnetism. We deducted that all magnetism is caused by current/moving charges. However, only charges moving in a given direction will cause something to be magnetic. This boils down to: Moving charges in a net direction will exhibit magnetic properties. This led us to once of the most important questions of Unit 7: Why does a paperclip stick to a magnet?

To start, we know that a magnet has domains spinning in a net direction simply because it is a magnet. We also know that the paper clips domains are spinning in random directions simply because it is not a magnet. The magnet has a magnetic field spinning around it, when the magnet comes close to the paperclip the domains of the paperclip start spinning in the same direction of the domains of the magnet. Now the paperclip is aligned with the magnetic field of the magnet. The paperclip now has a north pole and a south pole, the north pole of the paperclip is attracted to the south pole of the magnet, thus the paperclip sticks to the magnet!

From this question we can deduct a few things:

1)    The paperclip is now a magnet

2)    Opposite poles attract each other

3)    Like poles repel each other

Learning about magnets led us to talk about the Earth’s magnetic field. The Earth is actually a giant compass. The Earth, just like a magnet, has a north pole and a south pole, and all the charges move from south to north. The charges exit earth out the North Pole and circle back around earth into the South Pole. When the magnetic field surrounds earth, it actually protects it from harmful rays. We know this because all moving charges feel a force in a magnetic field when they are moving perpendicular to that field. For example, the northern lights, the northern lights only appear at the poles of the earth because that is the only place that cosmic rays are able to enter earth’s atmosphere. Thanks to earths magnetic field the cosmic rays can only enter the atmosphere at the poles because that is the only place that they are traveling parallel to the magnetic field. At the equator of the Earth cosmic rays are deflected because they meet the magnetic field at a perpendicular angle.

MOTORS:

One of the biggest activities of this unit was when we got to make our own motor! Making a motor was surprisingly a lot easier then I thought it would be. The materials we used were a battery, a magnet, a rubber band, two paperclips, and a coil of wire. The battery provided an electric potential difference so that there could be a current running through the coils. The coils, which were suspended above the magnet by the paperclips, would spin. The coils spun because current carrying wires are going to feel a force when in the presence of a magnetic field. The spinning coils were a motor. If we had attached wheels to either side of the wire then we would have a little car. Similarly, if we attached blades to the either end of the coils, we could have a blender or a fan. It is important to remember that with a motor we are putting electric energy in and getting mechanical energy out.

Right hand rules!

This unit we learned about two important right hand rules. The first tells us what way the magnetic field would wrap around a current carrying wire. The way your fingers wrap around your thumb represent the magnetic field while your thumb represents the direction of the current. The second right hand rule uses three fingers, your pointer, middle, and thumb. The middle finger represents the magnetic field; the pointer is the current, and the thumb the direction of the force!

A very similar concept to motors is generators, however they are the complete opposite. With generators we input mechanical energy and get electrical energy out of it. A generator works when a coil of wire is moved around a magnet or when a magnet is moved in and out of a coil of wires.

ELECTROMAGNETIC INDUCTION:

Electromagnetic induction is the reason that our credit cards work, metal detectors in airports work, and why stoplights change when cars drive up to them. When a car drives up to a stoplight there is a coil of wire in the ground. As the car drives over the coils of wire it induces a voltage. This voltage causes a current and this current acts as a signal telling the stoplight to change the light. The same thing goes for credit cards. A coil of wire is inside of the credit card machine. When the card is swiped the magnetic strip on the credit card changes the magnetic field and induces a voltage, which creates current, which acts as a signal and tells the computer the costumers credit card number.

TRANSFORMERS:

Transformers are those little boxes on appliances that either step up voltage, or step it down. In a transformer there is a primary coil and a secondary coil. The loops of the primary coil divided by the voltage going into the primary coils is equal to the secondary number of loops divided by the voltage going into the secondary coils. We know the power of the primary is going to equal the power of the secondary. However, depending on the type of transformer, the primary number of loops is going to be greater or lesser then the secondary number of loops and the opposite for the voltage. A mathematical equation could be written as 1 # of loops/1 volts = 2 # of loops/2 volts.

Some important formulas to remember for this unit would be:

P=IV (Power = (Current)(Voltage)

I=V/R (Current = Voltage / Resistance

*An important thing to remember for this unit was that when talking about generators, only Alternating Current works in order for electrical energy to be the resulting output. This is because with Alternating current, the alternating movement of electrons causes a change in the magnetic field, which is the catalyst for the flow of current. With Direct current, the electrons only flow in one direction, the lack of change would cause no change in magnetic field and a current would not be created.

PODCAST:

Motor Blog

 During class we learned how to make a simple motor using a battery, rubber band, magnet, two paperclips, and come copper wire. The two paperclips were attached to either side of the batter by the rubber band. The copper wire was coiled and was held in the air above the magnet, which was stuck to the battery, by the two paperclips attached to each side of the magnet. This was the setup of our motor. The battery caused electrons to flow through the copper wire, which reacted to the magnetic field surrounding the magnet. The paper clops acted as conductors as well as a source of suspension for the wire. In order for charges to flow into the wire, the top layer of the wire needed to be scraped off in order to allow charges to run through the copper wire and complete the circuit. The armature needed to be scraped only on one side so that the wire would turn consecutively in one direction. If the wire had been scraped on both sides then it would simply turn back and forth. The motor turns simply because a current carrying wire is feeling a force from a magnetic field. If the current was flowing from left to right then the motor would turn coming towards you. If the current was flowing from left to right then the coils would move away from you. If you attached wheels to either end of the copper wire then it could be used like a car. If you attached blades instead then the motor could be used as a fan or perhaps as a blender or blending sort of contraption.

Magnet Resource

This video explains the northern lights and even goes to explain the magnetic fields of other planets and even the galaxy. Bill explains how the northern lights are so by explaining the characteristics of Earth's magnetic field. Through this video we learn that the strength of a planets magnetic field is directly related to the amount of metals in the planets core.

Unit 6 Reflection

This unit in physics we learned about charge, polarization, and electric fields! We learned how real life situations such as hair standing up after pulling a sweater over it, or why a balloon sticks to a wall after rubbed against hair, is so.

Charges:

Charges are such by the make up of protons (positive ions) and/or electrons (negative ions). Protons and electrons attract each other while protons and protons or electrons and electrons repel each other. There are three ways that an object could be come charged: friction, direct contact, and induction. When you pull a sweater over your head, the sweater steals electrons from your hair through friction. When this happens your hair is filled with protons, since protons and protons repel each other, your hair stands up!

Polarization:

When discussing polarization, it is important to recognize what a conductors and insulators are. Conductors let charges move through them, insulators stop charges from moving. An object becomes polar when the charges are separated. For example, if you stuck a rod of electrons near a neutral object, all of the protons would move closer to the rod and the electrons would move further away from it. When the negative and positive ions are separated like this, the object is polarized. This is the reason that saran wrap wont stick to metal bowls. Metal is a conductor and will send all charges to the ground whereas glass and ceramic bowls will polarize.

We applied all that we learned about electricity to everyday usage. We learned about lightning rods, light bulbs, circuit breakers, outlets, and more!

Lightning rods:

We learned that lightning rods protect structures because of their ability to prevent fires by their ability to send charges from lightning to the ground. Lightning rods are pointy metal rods that are placed on the roofs of buildings. Protons collect of the points of the rods and when lightning strikes they attract the negatives charges coming towards the ground from the clouds. When the lightning strikes the rods all the charges are send to the ground through a cable that is connected to the bottom of the rod and the ground.

Light Bulbs:

One of the many labs we did this unit required us to light a light bulb using only a battery and some wire. Through this lab we learned that the wire must be connected to the bottom of the bulb and the side of the bulb. These two places are where the wires need to be in order to complete the circuit and light the bulb. Similarly we learned that the wire in the middle of the bulb is called the filament. Based on thickness and length the filament will have either a high or low resistance and will determine how much current can run through it, affecting how bright the bulb is.

Circuit Breakers:

In this unit of physics we learned why circuit breakers commonly trip when you use too many appliances. Circuit breakers are wired as series circuits, which mean as more things are used the current remains the same, while the resistance increases. On the contrary houses are wired in parallel so when you use more appliances, the overall current being used increases. When this current gets too high it could potentially start a fire. In order to prevent a fire from happening, the circuit breaker trips. The circuit breaker flips a switch in the circuit and stops all appliances from working.

Outlets:

This unit we learned about voltage and how our outlets in America are 120-volt outlets. We learned that outlets in Europe have a higher voltage so when we take our appliances to Europe using them is actually dangerous because our appliances are not designed to handle the amount of volts that European outlets emit. 

Mousetrap Blog

My mousetrap car traveled 5 meters at a time of 2.59 seconds. This puts my teammate and I in first place.

Here is a video that shows my mousetrap car run. 

a) Newton’s first law of motion states that an object in motion or an object at rest wants to stay that way until and outside force is exerted upon it. This law is applicable to the mousetrap race at the starting line and at the finish line. Our car begins at rest and would like to stay that way, but when we engage the mousetrap, the string that is connected and coiled around to the back axel forces that axel to turn along with the wheels propelling our car foreword. At the finish line, our car is in motion and wants to remain that way, however the friction between the wheels and the ground slows the car down and eventually stops it. Newton’s second law, a=f net/m (acceleration is directly proportional to force and inversely proportional to mass) proved helpful for my team. When building our car, Isabelle and I used very few materials and kept our car simple. Because of this our car had a smaller mass, which allowed it to have a greater acceleration. Newton’s third law, which states that every action has an equal and opposite reaction is applicable to our mousetrap car similar to the horse and buggy problem. When the axel is turned because of the force the mousetrap pops with, the wheels are going to push the ground backwards and the ground is going to push the wheels foreword.

b) The two types of friction present are with the wheels and the ground, and the axel and the wheels. Attaching the wheels to the axel without them moving was challenging at first. Originally Isabelle and I tried to wrap balloons around the axel and fasten the wheels (cds) over them that way. This proved to be unsuccessful so instead, we used tape and that worked out well. The second problem we encountered with the friction was with our wheels and the ground. Our wheels are CD’s so the friction between them and the ground is little. To fix this problem we took the centers of two balloons and stretched them around the CD. This created better friction and propelled our cars nicely and smoothly.

c) We had always planned on using four wheels. That seemed to assure the smoothest ride and best stability along with simple construction. On each axel we used a regular sized CD. Using larger wheels would have been helpful because they cover a larger distance per turn of the axel. However our wheels worked out just fine. Smaller wheels would have been detrimental to our mousetrap car because it would have required our axels to turn more times because they cover a smaller distance per rotation. 

d) Energy is essential to make our mousetrap car move. Energy is neither created nor destroyed with the motion of our car. Energy is transferred from setting off the trap and releasing the potential energy it is holding. When set, the mousetrap holds a large amount of potential energy. When the mousetrap is set off, that potential energy becomes kinetic energy and shoots the car into motion.

e) We did not extend the length of our lever arm. When we test ran our mousetrap car it went 5 meters fairly fast. Seeing this we decided it wasn’t necessary to extend ours. However, I noticed that a great deal of the other groups extended their lever arm. Doing this they were able to increase their torque and use the greater distance to uncoil their string from their axis more quickly.

e) Rotational inertia was important to our mousetrap cars because it determined how quickly the wheels began to turn. Having solid wheels is key because they have a lower rotational inertia and will begin to move more quickly. The lower rotational inertial a car had, the greater rotational velocity it would have because it would be easier for the wheels to rotate. Each wheel of our car needed to have the same tangential velocity in order for the car to travel in a straight line. The straighter the line your car travels in, the quicker it will obtain a traveling distance of 5 meters.

f) We cannot calculate the amount of work that the spring does on the car because the distance is not measureable by us. We cannot calculate the amount of potential energy because the potential energy is directly related to the amount of work that the spring can do. We cannot calculate the kinetic energy because we do not know that amount of potential energy. Similarly we cannot calculate the force because the mass and the acceleration of the spring.

Reflection:

a) Our final design was almost exact to our original design. The only difference was that instead of using balloons to fasten our wheels to the axel, we used tape.

B) We didn’t encounter too many major problems. The only problems that we faced were when the balloons failed to fasten our wheels, and to fix it we tried tape which work well. And when we engaged our mousetrap the string would get caught, so to fix that we held the trap down and released it manually rather then with the sensor.

c) In the future I would keep everything the same and maybe extend the lever arm a bit. Personally I am very satisfied with the outcome of my mousetrap car and I am content with everything that we have. 

Unit 5 Reflection

This unit in Physics we learned about work, power, potential energy, kinetic energy, and machines. Beginning with work, we learned that work = force X distance. But, this is only so when the force and distance are parallel and not perpendicular to each other. Work is measured in the unit of joules. After learning about work, we learned about power. Power = work / time. Power is essentially how quickly one is getting work done. Power is measured in watts. 746 watts is equal to one horsepower. We commonly hear the work horsepower used when talking about cars, specifically the power of their engines. Cars with a big horsepower can go faster quicker because their engines do work faster. Next, we moved on to Potential Energy. PE is energy stored and held in readiness. It is called “potential” energy because it is in a state where it has potential to do work. An objects PE is determined solely on its position. To calculate an objects PE one can use the Formula, PE = (mass)(gravity)(height). Moving on, we learned that Kinetic Energy is energy in motion. KE is dependant on an objects mass and speed. KE = 1/2mv^2. The change in KE is equal to the KE final – the KE initial. Or, the change in KE is also equal to work. If an objects speed is doubled, the KE is quadrupled. When learning about energy, it was important to know that law of Conservation of Energy. This law states that, “energy cannot be created or destroyed; it may be transformed from one form into another but the total amount of energy never changes” Post energy, we began to study the use of machines. For example, the ramp is a simple machine. Machines make doing work easier. Take the ramp for example. The ramp is going to increase the distance in which you are doing work allowing you to use less force. We know this because we know that the amount of work that you put into a machine is going to equal the same amount of work that you are going to get out. Work in = work out If you put a certain force with a certain distance in a you ultimately increase the distance with a machine your force needs to be lower in for to be equal to the previous work. Fd=fD. While machines are useful, they are never 100% efficient. Some energy will always be transferred through various things such as heat due to friction, motion or vibrations, light, or even sound.

This unit I found to be fun. Work and power were both things that I was somewhat familiar with and both were easy to relate to the real world. This unit I found myself misunderstanding some questions on the quizzes, which was 100% avoidable. I could benefit from asking questions if I need clarification during a quiz. Otherwise I feel like this unit went well for me. 

Unit 4 Picture

This picture is an example of centripetal force. The swings on this ride are connected to the center consul which keep them towards the center. This picture is real life example of the flying pig demonstration we did in class. If one of the swigs were to come off, that swing would fly in a straight line that is tangent to the path it was previously traveling. 

Unit 4 Reflection

Unit Reflection:

In unit 4 we learned about torque, rotational and tangential speed, rotational inertia, center of mass, center of gravity, centripetal force, and centrifugal force. To start this section we learned about rotational speed, which is the number of revolutions that are made in a certain amount of time, and tangential speed, which is the distance covered in a certain amount of time. We learned that while two people on a merry go round may have different tangential speeds, they would both have the same rotational speed. We applied our knowledge of tangential speed to roller derby and discovered that the purpose of “the whip” move is so that the skater being whipped could gain a greater tangential speed and therefore pass her opponents. Similarly we leaned that if you increase the size of your tires on your car you could be driving at a faster speed than your speedometer reads. An objects angular momentum has to do with how much mass is closer or further form the axis of rotation. An object with a larger amount of mass away from the axis of rotation is going to move slower than if the mass was closer to the axis of rotation. An object with more mass further away from the center is going to have a greater rotational inertia because it is going to be more difficult for the object to begin to move. If the mass were more towards the center however, the object is going to have a lower rotational inertia and be easier to begin moving. Next we learned about torque and center of mass. Torque causes rotation. Torque = lever arm X force. The longer the lever arm that you are using to turn an object the smaller force you are required to apply and vice versa. We then learned that because of center of mass, when we put on our backpacks, we subliminally lean foreword so we don’t fall. Because we increase our mass behind our natural center of mass we need to lean foreword and balance out our new center of mass. This action keeps us form falling over. As long as our center of mass remains under us we will stay standing. We also learned that the leaning tower of Pisa does not fall over because its center of gravity is being supported by it’s base. In other words the center of gravity is within the base of support. We then moved on to centripetal and centrifugal forces. Centripetal force is the center seeking force when you are turning on a curve in your car. The feeling of fling that you feel when you are turning on this curve is the centrifugal force. The center fleeing force you feel is the fictitious force. We learned that during the spin cycle when your clothes are in the washing machine, the water leaves the basin through little holes not because of a force but because of a lack of force present. Personally, I struggled with this unit more than I have with the others. Coming and asking questions in the morning would have been beneficial. 

Center of Mass Resource

http://www.youtube.com/watch?v=DY3LYQv22qY

In this video, people throwing objects demonstrate center of mass. When the objects are thrown in the light they seem to be moving all over the place, but when the lights are turned off and the center of mass is painted it looks as though the object is moving through the air smoothly. With the lights off you can clearly see the center of mass, whereas when the light are on it is more difficult to see. 

Angular Momentum Resource

This video clearly demonstrates angular momentum. You can see how when the mass is closer to the axis of rotation of the object the speed at which it spins increase. This is similar to an ice skater, gymnast, or a diver. In order to spin quickly all three of these sports require the athlete to pull all of their mass in towards the axis of rotation.