Top Ten Coolest Physics Concepts in Life

This year in Physics, I went through many hard units where I was unable to grasp the material the way I should have been. But eventually, I was able to understand it and even had a few Eureka! moments. What helped me the most was when I was able to see and understand physics in real life.

1. Newton's First Law
An object in motion will stay in motion if no other force acts on it, and an object not in motion will not move unless an outside force acts on the object. The way I understood this concept was with the example of a coffee mug on the back of a car. The coffee mug is not moving, just chilln' on the back trunk. It wants to stay that way because its too lazy to move. But, there is an outside force that acts on it: the car starts to move forward. When the car moves forward the coffee mug simply falls off because instead of moving with the car, it  continues to not be in motion while the car moves. This is the coffee mugs inertia.

2. Tides
After learning about tides, we were let out for Christmas break, and I took a trip to the Maldives. Here, I saw the concept of tides all around me (literally all around me, the island was only 500 m both ways). The tides change 4 times a day because the earth is rotating and all parts of the earth are either feeling the attracting, or not feeling it, towards the moon. This is why opposite sides of the earth feel it at the same time: They are aligned with the direct force from the moon, therefore the water becomes concentrated in those sides, while the sides of the earth that don't feel the force, have low tide.

3. Newton's Third Law
His third law states that for every action there is an equal and opposite reaction. I saw this in my own life during this soccer season. When I went to shoot a goal, I was not only kicking the ball and because it was put in motion, was forced to move. The force went both ways: foot hits ball, ball hits foot. While learning about Newton's third law, we learned about how a horse and carriage works. We knew that for every action there is an equal and opposite reaction, so we could conclude that both the horse and carriage pull each other with equal forces. The reason the horse and carriage are able to move forward is because the horse pushes the ground harder than the carriage does. 

4. Electromagnetic Induction
The way we learned about this was through a real life example of a car at a stop light. Below the surface of the road is a coil of wire right before the intersection that is connected to the light. A car has a large magnet, so when the car pulls up to the intersection, it moves over the coil of wire. This causes the magnetic field to change. this change induces a voltage which causes a current. This current send the single up to the light to change. Electromagnetic induction is seen all over in everyday situations, such as airpower security detectors, electric guitars and credit card machines. 

5. Acceleration 
Objects are accelerating all the time while moving. Acceleration is the change in velocity over time. Acceleration is measured in m/s^2. We see acceleration in cars especially. How fast they are getting faster or how fast the are getting slower. When a skydiver jumps out of a plane, gravity accelerates the diver at 10m/s^2. What I struggled with the most was that there can be an increasing speed but a decreasing acceleration. This just means that an object might still be accelerating, but it is just getting faster slower. 

6. Center of Gravity
I saw this physics concept is many sports such as football and wrestling. To keep from being knocked over in football, the players keep their legs shoulder width apart. They do this because when they open their stance, they are widening their base of support. Then someone has a wide base of support, they're harder to knock over because to do so, their center of gravity would have to be moved over their base of support. These two boxes will fall over because their center of gravity is outside their base of support.

7. Rotational Velocity
Ice skaters have mastered the idea of rotational inertia in physics. They begin to spin with their legs and arms away from their axis of rotation. When they do this though, they have a small velocity. They then bring their arms and legs into their body, and their velocity increases. This is because they brought their mass closer into their axis of rotation. this can be shown in the picture to the left where the ice skater brings her arms in from being far away, and her velocity increases.


8. Lightning/Rods
Being from Saudi Arabia, we don't really have rain or lightning storms often, but when I came to the US, I saw metal rods next to structures. In physics I discovered that lightning rods help protect objects from being struck by lightning. Lighting takes the path of least resistance to get to the ground because of the clouds negative charge and the earth's surface being positively charged. When the lightning rod is along side your house, the lighting is attracted to the rod instead of your house. Because the rod is higher up and metal, this is the path of least resistance, therefore the lighting takes it. The odd provides a direct path to the ground, and lets the electricity to be grounded.

9. Transformers
Transformers can be seen everywhere: computer charger, in cars, basically anything that needs electricity. A transformer has two parts: primary and secondary coils. The current running through the transformer is AC current because the current must be moving back and forth across the coils to induce a voltage which causes a current. In the coil of wire, increasing the amount of coils will increase the voltage and current and visa versa. To convert the voltage from the wall to your computer, which must go from a lot of voltage to a little, there must be a transformer.

10. Vectors
I used my knowledge of vectors, and applied it to my final coolest physic concept. I saw the use of
vectors when sailing. When the (water) current is strong, it is hard to fight its strength to the finish line. The example we used in class we one with a river. To get to the other side, and taking into account the direction of the river, the fastest possible path across the river would be to go at an angle up stream. When these two vectors are then added, the result is a straight line to the other side of the river.

Wind Turbine

For our final physics assignment, we made a wind turbine. My group made the most successful wind turbine, courtesy of the 800 turns in our coils. To make our turbine work, we had to make a generator from coils of wire and four magnets. During this project, we created electricity with magnets; this is known as electromagnetic induction. To make our turbine work, we had to induce a current in the coil of wire by changing the magnetic field around the coil. We changed the movement of the charges by putting the magnet there, which realigned the charges which were going in all different direction, to make them all move in the same direction, helping to spin the turbine. This change from mechanical energy to electric energy is what makes the turbine a generator.

The materials we used to make our wind turbine were:
water bottle
coil wires

disk magnets
square dowel
round dowel
LED
fender washer

screws
wood for the platform
glue

We cut a water bottle in half, to fit in the template we cut out, and then glued it to the top and bottom. The water bottle was used to make the turbine spin and thus cause a voltage. Next, we punched a hole into the two cardboard pieces, and put the sharpened piece of round dowel through it, and then let it rest on the top of screw to keep it standing up, and also to let it rotate freely. The most important (and difficult because I'm so bad at wrapping coil apparently) was next. We made 4 coils that connected to each other. Each individual coil had 200 turns, to make a total of 800 turns. We then glued these four coils down onto the wooden base. We then used the fender washers and disk magnets to align with the coils to induce the voltage. All the poles of the magnets were facing the same way so that the current would go in the right direction. Finally, we attached the end pieces of the coils to a LED. Our wind turbine successfully produces a voltage. 

What made our wind turbine so successful was the amount of turns in our coils. The more turns, the more easily a current can run through it. The only problem we had was wrapping the coil 200 x 4 times, and then successfully getting the coils off the cardboard that helped us shape it. Over all, this project was a success for my group. On the final test, I struggled with a question involving wind turbines because I didn't really understand the concept fully. With this project, I was able to understand the function for all the components, and am now able to piece them all together to understand why a wind turbine works. 

Unit 7 Reflection

This unit, we began learning about magnetism first. The source of magnetism is moving charges. The charges (electrons) are spinning randomly when not magnetized. Domains, however, are clusters of electrons all spinning in the same direction. Magnetism gives them a net direction. This happens when a magnet is brought near a cluster of randomly spinning electrons. In order for the direction to stay the

same, and because the magnet is much stronger than the cluster of electrons, the electrons are all forced to align so that the magnetic field can continue to flow. In an electron flied, there are two poles. The North and south pole. The magnetic field runs out of north pole, and then to the south.

The reason the charges are forced to move this way in a magnetic field is because: like poles repel and opposite poles attract. When the electrons leave the north pole, they are attracted to the opposite pole (the north pole) that they were just repelling. 

There were three big questions asked this unit:

How do you turn a paper clip into a magnet?

The Domains in a paper clip are random, and a magnet had a magnetic field. When the magnet is close to the paperclip, the domains align to match the magnetic field of the magnet. The paperclip now has a North and South pole. The North pole of the paper clip is attracted to the South pole of the magnet, and thus the paperclip sticks to the magnet

Are cosmic rays harmful or helpful, considering the Earth's magnetic field?

The cosmic rays are helpful because there is a field around the earth, and when a charge enters the field, it circles around the file lines, all the way into the North and South poles. All moving charges feel a pull from a magnetic field if they are moving perpendicular to it. Because of this, when a moving charge out in space is moving perpendicular to the Earth's field lines, it gets sucked in, and because of the right hand rule, starts spinning around the field lines, right into the North and South poles. This is what causes the Northern Lights. We can only see them in the North and South poles because the charges are following the field lines into those poles, and that is where they are the most concentrated.  

How does a credit card machine read your card?

The credit card has a magnetic strip, which has a code. When swiped, the coils turn causing a current. The computer reads this current that is caused by the coils and counts the number of coils, letting the machine read your card. 

The right hand rule that I mentioned in the Norther Lights question, can be demonstrated in the picture:

The thumb represents the direction of the current of moving charges. The fingers curls around the thumb, representing the direction of the magnetic field. 

Electromagnetic Induction is the process of inducing voltage by changing the magnetic field of the loops of wire. The more loops in a wire, the greater the voltage is induced. Faraday's Law states that

the induced voltage in a coil is proportional to the product of its number of loops, the cross-sectional area of each loop, and the rate at which the magnetic field changes within these loops. There are three ways that voltage can be induced in a wire:

1. moving the loop of wire near a magnet

2. moving a magnet near the loop of wire

3. changing the current in a nearby loop

All of these methods involve changing the magnetic field in the loop of wire.

A transformer is a device used for increasing or decreasing voltage or transferring electric power from one coil of wire to another through electromagnetic induction. A transformer has 2 coils of wire. There is a primary, which is the input because it is directly connected to the power source. The other is the secondary. Electric current flowing through the primary coil causes a change in the coil's magnetic field. This spreads, inducing a voltage on the secondary coil. Voltage causes current, therefore, there is a electric current being transferred between the 2 coils. In order for the current to work, the transfer of electricity must be constant, and the only current that gives a constant surest is AC. AC current is constantly changing, while DC only goes one way, which wouldn't let the transformer work. 

Primary and secondary voltage relationship:

Primary Voltage    =   Secondary Voltage 

# of primary turns       # of secondary turns

energy is conserved, so power of primary = power of secondary. VI = VI. 

The last thing we learned about in this unit were motors and generators. Motors take electric energy (the input) and through electromagnetic induction produce mechanical energy (the output). Generators, on the other hand, take mechanical energy (the output) and with electromagnetic induction, make electrical energy (the input). Genorators produce a current as a result of motion. While the motor makes motion as a result of current.

Motors Make the World go Round

In this lab, we constructed a motor using a battery, a coil of wire, a paperclip, and a magnet. Each had their own function in making the motor function properly.
Battery: power source for the motor
Coil of wire: carries the charges and acts as a circuit connector
Paperclip: creates a domain that allows the current to continue the run through it
Magnet: provides a North and South pole for the current to flow through

To make the motor work, we had to strip both ends of the coil. We did this because the current was flowing out of the North pole of the magnet, going up towards the motor loop and through the coil ends into the paper clips, then back around to the South pole of the magnet. The motor turned because of the magnetic pull created by the magnet. This is because all the charges in the wire were moving the same way, but since the wire was coiled, the current would technically be in different directions. The vertical loop felt the force of the magnet in opposite directions on the top and the bottom sides so there was a torque on both ends of the wire, causing it to rotate. If the loop was horizontal, it would not feel this force in a perpendicular way and there would be no rotation. 

The motor is very small, in fact to small to power anything, therefore, we used this motor only for educational purposes. 

Here is a video of our motor working in action: