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This fall, I will be headed down where the weather is warmer. I will be two hours from the Atlantic Ocean, one way and two hours from the Gulf Coast in the opposite direction. This means lots of time at the beach for me! So, I decided to explore where I will see physics at the beach!

1.

When I go to the beach, I put my chair right along the edge of the water. I happen to fall asleep and when I wake up, the waves are crashing in my lap. What causes this? TIDES!!! 

Tides are caused by the pull of gravity. There are two high tides per day and two low tides per day. I happened to fall asleep as the tide was going from low to high. 

Because the distances are different, point A and point B will experience different forces from the moon's pull. We know that Force and Distance are inversely proportional.

Therefore, 

>>Since B has a greater distance, the force will be lesser

>>And since A has a lesser distance, the force will be greater

This difference in force is what causes a tidal bulge.

2.

As I walk to the beach, I carry a chair and a bag. As I am walking with these things, they start to feel pretty heavy. I must be doing work, right? NOPE! Not according to the physics definition. In physics Work= Force* Distance and the work and distance much be parallel. When I am carrying my chair and my bag, the force is going upward but my distance is forward. So, I am not doing work. However, when I walked up the steps of the beach access, my force and direction were parallel. So, work was done. 

3. 

When I go to the beach, I carry a portable fan with me. When it gets too hot, I take my fan out to cool off. As I watch the tiny blades spin, I wonder how this fan works. 

The fan spins because inside of this fan is a motor. Motors change electrical energy (supplied by a battery in a portable fan) into mechanical energy, which is the fan blades spinning. The electricity runs a current through a wire which feels a force in a magnetic field. This force causes a torque, causing the blades to spin.

4.

My friends and I find a cliff that overlooks the water. He decides he wants to jump from the cliff. However, there are rocks below the cliffs. In order to make sure that my friend clears the cliff we have to calculate the time it takes him to reach the water given that height of the cliff. Once we find the time, we can calculate the horizontal distance that my friend will travel. 

5.

At the beach my friends and I decide to play a game of tug o' war. With my physics background, I am able to inform my team on how to win. With my knowledge of Newton's Third law, I know that during tug o' war there are action-reaction pairs. Both teams will pull on each other with equal force. However, the teams can push against the ground with different forces because the pushes against the ground are not part of the sam action reaction pair. The team with the greater push on the ground will be pushed back by the ground with that same force and thus win the game. 

6.

My friend decides to pack a snack for the beach. She puts the snack in a metal bowl and covers it with cling wrap. When she gets to the beach, she sees that her snack has spilled all over the bottom of her bag. She did not realize that the cling wrap will not attach to a metal bowl. This is because cling wrap works through polarization. When the wrap touches a ceramic bowl, it will polarize and the like charges will attract and the wrap will stick to the bowl. However, when the wrap touches a metal bowl, it will not polarize because it is a sink for the charges on the wrap. 

7.

I get tired of the beach and decide to venture to an amusement park on a peer nearby. I decide to race go karts. As I round the corner of the track, I think back on my days in Ms. Lawrence's physics class and recall learning about centripetal force. I know that my cart is able to round the curve due to centripetal  force. Without this force, my kart would continue to go straight. 

8.

At the end of the race, I stop my cart. As I am about to unbuckle, my friend doesnt apply his breaks soon enough and runs into the back of my kart. My kart starts to move forward. Why is this? Conservation of momentum. Conservation of momentum states that momentum can be made or destroyed. Conservation of momentum states that momentum can be made or destroyed. This means that the momentum of his kart before he hit me will equal the momentum of both of our carts after he runs into me. 

9.

My friends and I stay at the beach longer than we planned. We ended up being at the beach until night time. This is when we begin to notice the heat lighting in the sky. 

Thanks to my physics class I know what is causing this lightening. The movement of particles in the clouds causes friction which causes the cloud to polarize. Because the electrons move to the bottom of the cloud, the positrons from the ground become attracted to the cloud, therefore polarizing the ground as well. The cloud and ground want to equalize, so once the pull builds to a certain point, an electric shock will transfer charge to equalize them, which we see as lightning

10.

We decide to return home because of the lightening. When we get home, we realize that none of the appliances in the kitchen are working. I know that all of these appliances are attached to the same fuse. I know that the fuse is attached in series to all of the appliances which are wired in parallel. I go to the breaker box and see that the fuse attached to the appliances in the kitchen is broken. I replace the fuse knowing that once I do, power would be restored to the kitchen. 

Wind Turbine

Part 1

Recently in physics we made a wind turbine as a project.

In order to build this turbine, we had to have a basic understanding of the following physics concepts

- Newton's Laws-
          -Newton's first law- An object in motion will stay in motion unless acted upon by the outside         force. In the turbine, we had to reduce the friction in order to make the blades rotate more easily. If there was a high amount of friction, the fan blades would not rotate.

         -Newton's second Law- According to Newton's second law, acceleration is directly proportional to force and indirectly proportional to mass. If my group were to have out too many magnets on our axel, the blades couldnt have accelerated because of too much mass.

         -Newton's third law- As the fan blades are pushed by the wind, the blades push back with an equal for according to Newton's third law.

-Torque- In order for the blades to rotate, there must be torque. Without the rotation of the blades the magnets wouldnt move and there would be no electricity.

-Friction- Like I stated in my blurb about Newton's first law, there will be friction. In order to build    the turbine, one must know where they should increase friction and where they should decrease friction. For example, when building a turbine, you would want a lot of friction between the wind and the blades but not very much friction on the axel.

-Electromagnetic induction- Electromagnetic induction is the physics principle that the idea for the  turbine is based upon. When a magnet moves around a current carrying wire it changes the                 magnetic fields of the wire which induces a voltage. That voltage causes a current.

-Energy conversion- In a turbine, there is mechanical energy, the rotation of the blades, being turned   in to electric energy.

Part 2

Here is a view of our entire turbine from the side. Our base was made of PVC pipe.

Here is a picture of our coil placement. Our coils of wire were wrapped around a cardboard box and inside the box were the magnets which were being turned as the blades were turned.

Here is a picture of our magnets. They were located between the coils of wire. They were attached to the axel that was attached to the blades of the fan. As the blades turn, the magnets turn inside the wire coils. 

Here is a picture of our overall turbine and blades. The blades would have been better if they were angled to catch more wind. Our blades were made of a plastic bottle and they were attached to a wooden mount and the axel was a metal rod. 

Part 3

- Our turbine produced .002V and .002A. 

-We, sadly, were not able to light a lightbulb. We did not produce anywhere near enough current to light a light bulb.

Part 4

Things that effect the the voltage:

-The size of the magnet- We used really big magnets in our turbine. The large magnets have a larger magnetic field which would create a bigger voltage. However, the magnets were super heavy which weighs down the axel and makes it harder to rotate.

-The rotation of the magnets- The faster that the magnets rotate. If the magnets move faster, the more voltage is produced. However, since our magnets were so heavy they did not rotate quickly.

- Space between the coils and the magnets- If there is a large space between the magnets and the coils of wire, the less voltage will be produced. 

Here is a video of our turbine in action. However, it is likely that the video will not work. I'm working on fixing that and it will be up as soon as possible. 

If  I could redo this project, I would change the blades so that they catch more wind. I would also suggest that you dont use really heavy magnets.

Unit # 7 Summary

During this unit we covered five main topics:
1. Magnetic fields and poles
2. Magnetic domains
3. Currents and magnetism
4. Motors and generators
5. Transformers

Magnetic Fields and Poles

Magnetism is a force caused my moving particles. Moving charges are the source of all magnetism.

Magnetic fields is the area that is effected by the magnet.

Magnetic fields have a direction.

Permanent magnet's field goes out through the north side of the magnet and into the south. As shown in the following picture

The reason why like poles repel and opposite poles attract is because of their magnetic fields. As shown in the following.

The earth also has magnetic poles. However, what we consider to be geographical north is actually magnetic south and geographical south is magnetic north. 

Magnetic Domains 

A magnetic domain is within amagnetic material in which the magnetization is in a uniform direction. This means that the individual magnetic moments of the atoms are aligned with one another and they point in the same direction.

Domains can be changed. For example, paper clips. 

On their own, paper clips are not magnetic. However, when they get near the magnet, their domains will align with the magnetic field of the permanent magnet. 

Currents and Magnetism 

Magnetic Force on Current-Carrying Wires:

When a wire is carrying a current, it has a magnetic field around it.  Use the "right hand rule" to find the direction of that magnetic field:

An electromagnet is a current carrying coil of wire.

 

The strength of an electromagnet is increased by the number of turns in the coil. 

 This also increases the voltage of the wire, increasing the current, therefore strengthening the magnet.

If the magnetic field is continuously changing, this is how a generator works. 

Motors and Generators 

Motors and generators have almost identical construction but opposite roles. 

Motors turn electrical energy into mechanical energy, whereas generators turn mechanical energy into electrical energy. 

In a motor or generator, a current runs through a coil, which feels a force because it is within a magnetic field. 

It feels this force because it is moving  and all moving charges feel a force in a magnetic field. 

The force felt by the wire causes a torque, causing the coil to spin.  

This spin produces usable mechanical energy.

DC (direct current) cannot be used for a transformer because the current it produces only moves in one direction whereas the AC (alternating current) continuously changes the direction of the current, which causes the change in the magnetic field. 

If a DC current were used, the generator would only work briefly when turned on ant turn off, where as an AC current constantly goes back and forth. 

Transformers

Transformers are used to increase or decrease voltage through electromagnetic induction  The small box connected to your computer charger is actually a transformer. 

The formulas you need for equations about transformers are 

# of Primary Turns/Primary Voltage

 =

 # of Secondary Turns/Secondary Voltage

Power Primary = Power Secondary

because Power = Current * Voltage,

IV primary = IV secondary

A transformer is simply made with two coils of wire. The number of turns in the wire is directly proportional to the voltage induced. The more turns in the wire, the more voltage there will be. The less turns the less voltage there will be.

Motors

For the past couple days in physics we have been learning about and making motors.

There are two necessary components of a motor, a current carrying wire and a magnet.

The current carrying wire feels a force from the  magnetic field, creating a torque.

The motors we made consisted of a wire coil, a battery, a rubber band, a magnet and a couple paper clips.

The motor looked something like this

An example of when a motor is used is in a car. A motor is what causes your wheels to rotate. 

Here is a video of my little motor in action.

Unit Summary # 6

During this unit we talked about six major topics:

1. Charges and Polarization(Coulomb's Law)
2. Electric Fields
3. Electric Potential/Electric Potential Difference
4. Current/Types of Current
5. Types of Circuits 
6. Ohm's Law  

Charges/Current/Coulomb's Law

 Objects have protons and electrons. When they have more protons than electrons or electrons than protons, they become positively or negatively charged, respectively. 

Things that have like charges repel each other while things with opposite charges are attracted to each other.

How do these charges travel and move? There are 3 ways:

1. Direct contact (shocked someone by touching them)
2. Friction (furry puppy below)
3. Induction charge without contact (lightning)

This dogs fur becomes charged through friction

Polarization

When an object is polarized, it is not charged, the charges are 

simply rearranged.

Here is an example:

The charged balloon comes in contact with the wall and the wall is

 polarized. 

This happens because of the like charges repelling each other. We 

can see this interaction in the formula for Coulomb's Law which 

states:

F= (k q1 q2)/d ²

where q stands for charge

The closer the like charges get, the more the charges repel. If the

 charges are opposite, the charges will attract with that same force,

 which is why the ballon sticks to the wall. 

Electric Fields

Electric fields are the area around the charge that can influence 

(push or pull) another charge.

How do we draw electric fields?

·       If a positive charge were close to the positive charge on the left, it would repel away

·     If a positive charge were close to the negative charge on the right, it would be attracted inward.
And notice how as you travel further from the charge, the lines get farther apart. This indicates the strength of the push/pull decreasing.

Current

Current is the flow of charge

Charge flows when there is a difference of potential energy between two points, and it will continue as long as there is electric difference between these two points.

It is important to remember that voltage causes current, current does not cause voltage

There are two kinds of current, AC and DC:

• AC - Alternating Current  
• switches direction
• used in batteries
• DC - Direct Current
• used in wall sockets

Circuits

Circuits are what allow the flow of the current. There are two kinds of circuits that we have learned about this year, series and parallel.

In a series, if you have multiple appliances, they are all part of one circuit. If one of the appliances goes out, the current stops flowing because the circuit is incomplete. Also, the current supplied is divided among the appliances. For example, if there were two light bulbs, they would both be dimmer than if there were just one light bulb.

In a parallel circuit, each appliance has its own circuit attached to the power source. If one appliance goes out, the rest keep working. This is the kind of circuitry you have in your house. However, parallel circuits can be dangerous because there can be a lot of current flowing through the wires which can cause them to over heat. This is why we have fuses. If there is too much current, the fuse will break, protecting your home.

Ohm's Law

All of this leads into Ohm's Law which states:

I=V/R

This means that the current equals voltage over resistance. More voltage, more current. More resistance, less current. 

Mouse Trap Car Madness

Over the span of the last week, Kennedy and I built a mousetrap car to apply the concepts we have learned over the year to a project.

Our car received 1st place in our class with a time of 2.98 seconds to travel a distance of 5 meters.

Watch the following video to see our little cart in action:

While building the car we took many physics conceptions into though. We had to show that we could complete the task at hand while also showing that we understood the physics behind it. The physics concepts we thought about when it came to the car are described below.

1. A light frame- We made a light frame out of popsicle sticks because acceleration = force/ mass. this tells us that the lighter the cart is, the greater the acceleration would be.

2. Large wheels- We chose large wheels(made of CDs) knowing that they would have a greater rotational inertia. Even though this is true, we figured that their greater circumference means that they travel a greater distance per rotation. The distance was what we were aiming to achieve over the speed, so we went with bigger wheels.

3. Axels- We used parts of mechanical pencils that were perfectly round. We chose these to promote ease of rotation. If the axels weren't perfectly cylindrical that would create friction which would cause the car to lose speed.

4. Ballons- We put balloons around our wheels to increase friction with the ground, because there has to be friction between the wheels and the ground in order to get the cart to move forward. There is an action reaction pair between the wheels and the ground. So, it order to get the car to go forward, we had to give it a greater push on the ground to make the ground give a greater push back.

5. Lever arm- We used a mechanical pencil attached to the wire of the mouse trap in order to have a longer lever arm. We used a lever arm to increase the time that the mouse traps snapping ability acted on the back axel. This allowed the cart to be moved by the stored energy for longer before it had to keep rolling because of momentum.

6. Yarn and Hook- We used yarn to attach the axel to the actually trap. This string is what caused the back axel to rotate as the trap closed. We applied the hook to create friction between the axel and the string. Without the hook, there wouldn't have been enough friction to make the axel rotate.

7. Mouse trap- Last but definitely not least is the trap. The wires of the trap have a lot of potential energy when it is pulled back. When the wire was released, it closes with a lot of energy. We were able to use the energy of the trap to make our cart move.

Physics Behind the Construction:

1. Newton's First Law: An object in motion(or rest) will stay in motion(or rest) until acted upon by an outside force. This is important because in order to keep the car in motion, you must take into account the outside forces and try to eliminate as many of them as possible.

2. Newton's Second Law: Acceleration is directly proportional to force and inversely proportional to mass. This is important because you must have a light car if you want it to accelerate quickly. 

3. Newton's Third Law: For every action there is an equal and opposite reaction. When building a mouse trap car, you have to keep this in mind, because there must be an action reaction pair between the ground and the car's wheels in order for it to move forward. 

The way our car related back to these laws are explained above.

Reflection

There are some differences between what we originally sketched and our final cart. The sketch shows the back wheels as CDs and the front as bottle caps. We should have also made the front wheels CDs a lot sooner, because thats what got our car over the line. We originally planned for the frame to light weight, which translated well to the final design. Other than the front wheels, everything worked out really well. Im very happy with the way our cart turned out. Especially because we won(only slightly competitive). If we had to do this project again, I would make sure to have the wheels all the same size. Also, I would make sure that they were all secured to the axels well, because we almost lost them a couple of times. Another thing I would do would be to better secure our lever arm, it got a little lopsided at times. At the end of all of it, I think our cart properly shows my knowledge of physics at work. 

Unit Summary # 5

During this unit, we covered the following topics:

1. Work and Power
2. Work and Kinetic Energy
3. Conservation of Energy
4. Simple Machines

Work and Power

The formula for work is

Work= Force * Distance

One thing to remember is that force and distance must be parallel to calculate work.

So, when you carry a box down a hallway, no work is done. When you first lifted the box, work was done.

Another example of work is walking up stairs.

You would multiply your force by the vertical height of the stairs to find the amount of work done.

Work is measured in joules(J).

One think associated with work is power.

The formula for power is

Power= Work / Time

The units for power are Joules/Second but thats a lot to say, so instead we use Watts(W).

Here is the video my group and I made about this topic:

Work and Kinetic Energy

Kinetic energy is the energy of movement

Formulas you need to know for this relationship are

Work= Change in KE

KE=1/2mv² 

Also, since work is equal to the change in KE, you must also know how to find that 

Change in KE= KEfinal - KEinitial

Conservation of Energy/Potential Energy

The Law of Conservation of Energy states that energy can be neither created nor destroyed, only converted.

So, when something is not moving, it has Potential Energy. 

Potential Energy is the energy of position. (height)

As this ball swings, it has varying amounts of potential and kinetic energy.

At the top of its swing, it has only potential energy.

Mid-swing, it has both potential and kinetic. 

The formula you must remember for this is

PE= Mass * Gravity * Height

Simple Machines

Today we have a misconception of how simple machines work. 

We think that simple machines reduce the amount of work you have to do.

This is not true.

Machines reduce the amount of force you use over a longer time. 

The ramp on the truck is a simple machine.

It would take a big force to lift something directly into the truck.

The ramp allows you to use a smaller force over a greater distance.

The work you put in will always equal the work you get out.