Top Ten Post

Top Ten Unforgettable Applications of Physics in Daily Life

1.     Moving Car and Newton’s First Law

In a moving car everything is moving at the same speed and has no outside forces acting on any of the items inside the car. According to Newton’s first law an object in motion will stay in motion unless acted on by an outside force and an object at rest will stay at rest unless acted on by an outside force. Since there are no outside forces on the objects you are able to handle them inside the moving car because they are all moving the same speed as the car.

2.     Car Breaks and Newton’s third law

When a car wants to stop the driver applies the breaks, I always thought that it just applied friction. Which it does but according to Newton’s third law that states every action has an equal and opposite reaction. The breaks apply friction and also accelerate the car in the opposite direction than it is moving. This adds to a net force in the opposite direction and makes the car slow down.

3.     The Electromagnetic Induction of Credit Cards

The credit cards have a strip of magnets in them that when swiped through the credit card machine that has loops of wires in it. Once the magnet passes through the wires it induces a voltage in the wire which in turn creates a current that creates a specific signal identifying the credit card and all the information associating with it.

4.     Newton’s third law and walking

When we walk we think nothing of it, but it is so interesting. According to Newton’s third law that every action has an equal and opposite reaction, when we walk we push back on the ground which pushes us back with the equal and opposite force making us able to move forward. This is what the physics of walking is.

5.     Lightning

That flash of light known as lightning is the positive charges accumulating on clouds. These opposite charges are attracted to each other and when enough energy is built up the two connect through the air. This results in the flash of light that we call lightning. It is very similar to the flash on a camera except on a larger scale.

6.     Hovercraft and frictionless surfaces

Newton’s first law states that an object at rest will remain at rest unless acted on by an outside force or that an object in motion will say in motion unless acted on by an outside force. Everything on our planet is affected by an outside force of air particles and other sources of friction, but if something negates that friction like a hovercraft then it will move continually. Early in the school year we rode on a mini hovercraft and saw this in action, the hovercraft would not stop unless someone was able to apply an outside force.

7.     Cushions and padding reduces the force

Cushions and padding increase the amount of time it takes to hit the ground and by doing so decrease the force that the person or object receives on impact. This is why air bags are big and fluffy, and why gymnastics floors are padded, so that the force will be decreased on the falling unit.

8.     Generating electricity changes mechanical energy to electrical energy

To generate energy we use electromagnetic induction which when a magnet passes through or over a group of wires induces a voltage in the wire and thus creates a current. Every power generating station in the world uses the same system, the only difference it what they use as fuel be it coal, water, or nuclear. These fuels generate steam from heated water or in some other way makes something spin magnets over wires which generate electricity for our society.

9.     Distance of the power lines

Power lines all over the country have to be farther apart than the wingspan of the largest bird in the area because if the bird lands on one wire nothing happens since it is not a complete circuit. If a bird were to touch to power lines at once then it would have completed a circuit with a voltage and a current would flow through the bird most likely killing it.

10.  Machines

Machines make the work that is done easier, but they never change the amount of force needed in the process. A machine like a ramp changes where the force needs to be applied. So instead of lifting a box 4 feet to the platform you only need to move the box up a foot at a time, but it will require more distance than just lifting the box straight up.

Wind Turbine

Background

            The wind turbine spins the magnet that creates voltage and then current through the process of electromagnetic induction. Electromagnetic induction is when there are loops and loops of wire and a magnet passes through or over the loops of wires it creates a difference in voltage in the wire which in turn generates current in the wires. The current generated depends on the amount of wire and the strength of the magnets magnetic field.

            Rotational inertia is the force that determines the ability and quality of the spinning body of the wind turbine. The mass of the rotating body was mostly in the center and the rest was distributed evenly around the edges

Materials & Method

            To make a wind turbine of your own you’ll need wire, magnets, washer, plastic bottle, cardboard, tape (preferably electrical tape), a paper clip, and a wooden rod. 

            Magnet placement

The magnets must be placed above or next to the wire and must all be facing (North/South orientation) the same way so that the wire feels the same force as the magnets spin around it. This induces the voltage of the wire so the magnet placement is very important to the actual effectiveness of the wind turbine. (see picture bellow)

            Coils of Wire

The wires must be placed into coils, multiple coils are fine, but they must be connected in a complete circuit for them to contribute to generating electricity. I strapped each coil to my base. The coils are very close to the magnets so that when they spin the force on the wires is greater. (see picture below)

            Wind Catching Device

To get the magnets to spin there needs to something that can catch the wind. My model was a vertical wind turbine and I used a plastic bottle to catch the wind. I cut the bottle in half and attached it to my spinning base on an offset. (see picture below)

            Overall Wind Turbine

The turbine was able to generate electricity, despite the minuscule value. The turbine was put next to a fan that was cranked up to the max. It was very interesting to see the entire thing spin and work just as the physics concepts tell us. (see picture below)

Results

My wind turbine generated .005 volts and amps. I was not able to light the lightbulb as I did not generate near enough electricity to make it function. (see video above)

Discussion

The factors that influence the amount of electricity generated is the amount of wire, the amount of magnets, and the speed of the magnets spinning. The more wire the more space there is for the magnets to induce a difference in voltage and more current is thus created. You can add more magnets which will increase the magnetic fields influence on the coils of wire and help to generate more electricity. You can also increase the speed at which the magnets are spinning to increase the rate that each wire is induced with voltage. These are the three ways I have discovered that helped increase the amount of electricity generated. This project was fun and interesting and there is a sense of satisfaction when you get your wind turbine to generate electricity. If I had to do this project again I think I would do most everything the same except I would add much more wire and magnets than I had on my last turbine.

Magnetism

Electromagnetic Induction

            This is the process by which a magnet passes over or through loops of wires and induces a voltage. This in turn creates current in the wire that can be used to send signals or to produce electricity. This process is used for traffic lights, credit cards, and transformers. Traffic lights have loops of wires in the ground so that when a car drives over them they induce a voltage creating a current that signals the traffic light to change colors. The credit card has a series of magnets on the back of it, the credit card machine has loops in it so that when the magnets on the back of the card pass through the loops inducing voltage in the wires that creates a very specific current that is identified only as that specific credit card. The transformer has loops of wires in it, one has more loops than the other and the transformer is able to convert the current to either AC or DC current. This process is also used to generate electricity, there are loops of wires and rotating magnets around them, the only requirement is the mechanical needed to rotate the magnets and generate electric energy.

Moving Charges

            Moving charges are the source of all magnetism. Moving charge determine the direction of the domains in the magnetized objects. Domains are the direction that the charge is spinning, when they are all in the same direction they are a fully magnetized. The more domains face the same direction the more powerful the magnetized object. When a permeant magnet is close to an object it’s magnetic field has an effect on the domains, it lines them with its magnetic field and magnetizes the object.

Magnetic Fields

            The magnetic fields travel inside the magnet from south to north, and on the outside the magnetic fields travel from north to south. The magnetic field affects any object with a perpendicular velocity. This is how the northern lights are created as the magnetic field of earth is perpendicular to the velocity of object except at the north pole of the earth where the velocity and the magnetic field are parallel and allow the object to pass through the Earth’s magnetic field and burns up in the atmosphere creating the colored lights.

Motor Summary

In physics class we made motors with simple batteries, paper clips, copper wires, and rubber bands. We bent the paper clips to be able to hold the wire over the magnet while still receiving current. Once this loop was created and the current flowed, the magnetic field applied a force to the current carrying wire and this force made the wire spin. This spin was caused by the current flowing through the wire at certain intervals. After looping the wire around and around to have a strong circle to have enough current to be affected by the magnet we scrapped the wired on the bottom of both sides, making a complete circuit that allowed the current to flow through. Since the direction of the current over the top of the magnet is perpendicular a force is applied to the wire the magnetic field applies a force away from the magnet. The wire feels this force and is turned since it is the only action it can take to move farther away from the magnet. Once it is turned the scrapped parts of the wire are no longer exposed to the paper clips and the complete circuit is broken and the flow of the current stops. This is the desired outcome, now there is no current for the magnates’ magnetic field to act on in the wire and there is no force put onto the wire. The force the wire felt at first should have been sufficient enough for it to spin all the way around and expose the scraped ends to the paper clips and again complete the circuit having current flow through it. The magnetic field applies a force to it again and the process repeats making the wire spin continually. If the wire were scraped to allow current to flow anywhere else as well as the one spot on the bottom the motor would not work. The magnetic field applies a repelling force on a current carrying wire. Initially this is needed to get the spin of the wire, but if the wire spins around and there is still current flowing through the wire then it will be repelled by the magnetic field. The repelling force on the wire will cause it to bounce back and forth, allowing neither side to approach the magnetic field.

The spin of the motor can be used to power machines and other thing. My motor could  maybe be attached to a small set of fan blades and spin them, but I don’t think that the small motor I created could be used to power anything substantial. 

Unit Summary

Blog post summary—Electricity

Electricity is made of charges some positive and others negative. Like charges repel each other while opposite charges attract each other. When they are stationary in the object the object is neutral or has no charge greater than the other. When an object becomes charged the opposite charges are pushed away and out of the object, through friction, touch, or induction and the object has an unbalanced amount of charges. The object is now polarized and attracts the opposite charges in other objects.

Induction is the transfer of charges through the air without the objects touching each other. This is how lightning works. The charges build up in the cloud through friction and the positive charges are pushed to the top of the cloud. The negative charges at the bottom of the cloud are attracted to the positive charges on the tops of buildings and the ground. When enough energy is built up the positive charges move towards the negative charges and the connecting of the opposite charges creates the light known as lightning.

Each charge has an electric field, an area that influences other charges based on the properties of the charge emitting the electric field. The electric fields are marked by arrows pointing the way that a positive charge would be moved within the electric field. So a positive charge has arrows pointing away because the positive charges would be pushed away if they came too close whereas a negative would be pulled closer. The distance is very important. Coulombs’ Law (F=kq1q2/d^2) states that the distance is squared and inversely proportional to the force between the charges.

Electric shielding works because of Coulombs’ Law makes the distance influence the amount of force. The force that a charge puts on the charge inside the shield depends on where the charge is inside. If it is closer to one side then those charges that are near it have more force on the charge, but the other charges still have a force on that charge they are weaker because of the distance. There are so many charges with weak forces that they balance out the charges with the stronger force thus keeping the charge in the inside neutral.

Volts are the amount of electric potential in an object and voltage is the difference in volts between two areas. Only when there is voltage is the energy flow through making the current move in the circuit. A circuit is when the area of different voltages is connected through something that allows the energy to flow through it. The energy that flows through it is called the current.

Circuits can be wired in different ways, parallel, series, and with fuses. The parallel allows multiple access points to the energy to be drawn at the same time while the series requires access points to be stacked on each other in order to add more appliances. Fuses are used for safety so that if too much current flows through the fuse breaks and the flow is stopped thus stopping any risks of damages. The parallel draws more current each time another appliance is plugged in while the series reduces the current flow.

The reason that the series is safer is because of resistance. In Ohms’ Law (I=V/R) it states that the resistance is inversely proportional to the current while the voltage is directly proportional. Each appliance that is plugged in adds some resistance to the circuit and in series this does not matter because it only makes the circuit safer. But in parallel it makes no difference because the more appliances are added the more current it draws despite the resistance. This is caused by each appliance in a parallel circuit to being wired separately and drawing more and more current.

Mousetrap reflection

My mouse trap car came in 3^nd place with a time of 3.25 seconds to travel 5 meters.

Newton’s first law states that an object in motion will stay in motion unless acted on by an outside force and an object at rest will stay at rest unless acted on by an outside force. This is the same for the car; just replace the word object with car. A car in motion will stay in motion unless acted on by an outside force and a car at rest will stay at rest unless acted on by an outside force. Our challenge was to be able to apply the outside force with the mousetrap.

Newton’s second law states that acceleration is equal to force divided by mass. The car has a defined force that cannot change, but the mass is still to be determined. My car was planned to have as little mass as possible to increase the acceleration and there for the overall speed. This was relatively successful as my car was light weight.

Newton’s third law states that for every action there is an equal and opposite reaction. This is the cause of the car moving. Below are the action—reaction pairs of the mouse trap car needed for it to move.

The mousetrap pulls the string and the string pushes the mousetrap

The string pulls the axel and the axel pulls the string

The axel pushes the wheel and the wheel pushes the axel

The wheel pushes the ground and the ground pushes the wheels

The wheels of the car relies on friction, this is good and bad. Good because the friction causes the wheels to move forward or backwards or in whatever direction, but bad because too much friction would cause the car to not be able to move at all. The challenge is to get the right amount of friction, enough to get the wheels to grip the ground and move, but little enough to not slow or waste the limited energy of the car.

The wheels of my car were CDs and they fit appropriately. The wheels also are a challenge they cannot be to large or the high rotational inertia will stop it from rotating but they must be large enough to have a lever arm large enough to rotate the wheels. The lever arm for the wheels is the distance from the axel to the edge of the wheel and must be big enough to produce the torque required to turn the wheels. The CDs that I used were very effective, they were the appropriate size. The limited force of the mousetrap was able to help create the torque that the wheels need to rotate.

The mousetrap is the force used to move the car and it has stored energy in it. The mousetrap has potential energy that, when released, becomes kinetic energy. This kinetic energy then drives the axels to spin and the wheels to spin moving the car forward. There is limited energy because of the law of the conservation of energy stating that the energy before is equal to the energy after. The mousetrap only stores so much energy and that is the total energy there is to propel the car forward.

Rotational inertia refers to who difficult it is to make something rotate or stop rotating. This refers to the distribution of the mass of the wheels and making sure that the rotational inertia is small enough to have the wheels move forward and continue to move forward after the force from the string has finished being applied. The speed that the wheels rotate helps determine the speed that the car moves, the rotational velocity of the wheels is different depending on the distance from the axis of rotation. The edge rotates faster than the center, so the bigger the wheel the faster the potential speed of the car. The tangential velocity is just a fancy name for the speed of the car. This also depends on the speed of the rotation of the edge of the wheel.

We cannot calculate the work done because no work was done; the spring and the direction of the car are not parallel. To calculate work the direction of the force and of the distance must be parallel. In this case they are not. And because we cannot calculate the work we cannot calculate the kinetic energy because of the change in kinetic energy is equal to the work. If we cannot calculate the work we cannot calculate the kinetic energy.

To my original design was what I used to create my car the only change I made was to the sting and axel. I detached the string from the axel and attached sandpaper to it so that the string would stick to it.

My only problem was that when I had the string attached it would stop the axel from rotating and stop the car. I fixed this problem by applying the explanation above.

If we were to do this project again I would plan to work on it about the same way I did this project. I created the majority of the car the first night and used the rest of the time to try and improve the design changing little things to see if the car could go faster.

In my next building project I will do most everything the same as this time because it worked well.

Link to video https://www.youtube.com/watch?v=WVKnyCNdDSo

Unit 5 Summary

Unit Summary 5

Work and Power

Work is the principle that when applying a force over a distance one uses energy, thus working. To be doing work the distance and the force must be parallel, no work can be done if the distance and the force are not parallel.  Work is measured in Jewels and is a form of energy. The formula is Work=force*distance. No matter how fast the work is done over the same distance the work stays the same. Power is the amount of work done over an amount of time and it is measured in watts. The formula is Power=work/time and 746 watts are equal to 1 horsepower.

Kinetic Energy

Kinetic Energy is the energy that causes something to move and it is measured in Jewels the same as work. The change in Kinetic Energy (KE) is equal to work, the formula is ΔKE=KEinitial-KEfinal and the formula to find Kinetic Energy is KE=1/2mv^2.

Conservation of Energy

The KE is the energy of a moving object, but when the object is not moving it also has energy, Potential Energy (PE). This is the measure of if the object began to move how much KE it would have. When an object is moving it has KE and also PE as these two types of energy transfer back and forth to each other. When an object is at rest it has 0 KE and 1000 PE, once it begins to move it has 800 PE and 200 KE and as the object speeds up the KE increases as well until the KE is 1000 and the PE is 0. There can never be more energy in a system than it starts with, in the case before the PE or KE cannot exceed 1000 because it started with 1000 units of energy, this is stated in the law of conservation of energy where the Energybefore=Energyafter.

Machines 

A machine, like a ramp changes the distribution of energy. Instead of having to lift a box up a meter in one go, one can push the box 4 meters with less force. The ramp increases the distance, but keeps the same amount of work because the box is still being moved up 1 meter, but over a longer horizontal distance. The single burst of energy needed to lift the box that meter is displaced over the distance of 4 meters at a constant or intervened rate. These are labeled work in and work out, the work in is the side with the longer distance while the work out is the side with the shorter distance.