Wind Turbine

In class we had the project to create a wind turbine.  A wind turbine is a type of generator.  And a generator is a device that turns mechanical energy into electrical energy.  This is done by inducing a current in loops and coils of wires.  When a magnet is moved over a coil of wire the electromagnetic field is changed and a voltage and current are induced.  So what a wind turbine does is it uses the mechanical energy of the wind to spin any amount of magnets over coils of wire.  The faster that the magnets move over the coils and the more magnets and coils that there are, the greater the induced current will be.   So the biggest challenge in all of this project was to get our magnets spinning quickly and closely to the coils in order to generate the most electricity.

                                                                        Motor 
In class I created a motor by using only a battery, a wire, a magnet, and some paper clips and rubber bands.  A motor is something that turns electrical energy into mechanical energy.  This is done when a current carrying wire experiences a change in its magnetic field, this is what the magnet is for.  When the magnetic field changes a torque is created.  This torque causes a rotation and it is that rotation that is used to do things.

                                          The Top Ten Times You See Physics In Football

"Down! Set...........  Hut!" The center snaps the ball and he and the other linemen take steps back to set up in cup pass protection. The center has great confidence that he will be able to block the blitzing linebacker that is shooting A gap.  This is because the center knows that he is much larger than the linebacker, and he also knows that an object at rest will stay at rest and an object in motion will stay in motion according to Newton;s first law.
 The QB now has the ball, he pushes off and begins to back peddle. But while he is doing so he thinks about how the only reason is is able to move is because he is pushing on the ground in one direction while the ground is pushing him back in the opposite direction.  This reminds him of Newton's third law which says that for every action there is an equal and opposite reaction.   Before he plants his feet and sets up to throw, the QB remembers how the vectors were used in his physics class to show the direction and forces during the cart and Buggy example.
                                                            
 The QB has set up, selected his target, and begins his throwing motion.  His arm extends up and out reaching nearly full extension.  He knows that if he wants to throw the ball far it will require a great force.  And one way to get a larger force is a greater velocity.  So by extending out his arm, the QB places the ball further from the axis of rotation (his shoulder).
By placing the ball further from the axis of rotation, it must have a greater tangential velocity in order to maintain the same rotational velocity.  What this results in is that the ball comes off of his hand with a high velocity and force that will propel the ball to its target.

As the QB releases the ball and watches it fly ever so gracefully through the air, he cannot help but to look up at the stadium lights and appreciate the physics that make night games possible.  He thinks back once more to that same physics class he had in high school where he learned about circuits and electricity.  He makes the assumption that the stadium lights are rigged up in a parallel circuit because some of the lights are on, while others are burnt out or turned off. He knows that a circuit must be complete in order for a current to flow, and is considering how a series circuit is inferior to a parallel because an entire series circuit will fail if there is any breakage at any point.  And at that moment his ribs experience some breakage as he is blindsided by the blitzing linebacker that the center was supposed to have picked up.
The ball is now flying through the air on its way towards the receiver.  (They say that the ball has a mind of its own, and this one happened to have a high school level understanding of physics concepts...)  As it is flying through the air it begins to realize that it is slowing down.   Thankfully the ball does not panic because it understands what is happening to it.  The ball is slowing down because it is experiencing air resistance.  And the ball knows that air resistance is determined by two factors, speed and surface area.  The ball can rest assured knowing that it has not gotten fatter, it has simply been going fast and so it was experiencing increased air resistance  causing it to slow down.
The receiver has just made his break on the ball and is preparing to catch the ball.   So naturally he thinks about how if he wants to decrease the force acting on the ball therefore catching it softer, he must increase the time it takes to come to a  stop in his hand.   The receiver understands that  p=mv  and he also understands that (delta)p=J and that to find (delta)p, you take p final- p initial.  Since J=F(delta)t  he increase the time that the ball is in contact with his hand in order to decrease the force.
The receiver has successfully caught the ball and turns his head to prepare to juke.  He sees that the safety is breaking down and is about to hit him.  The receiver then prepares for impact.  He bends his knees in order to lower his center of gravity and places his feet shoulder width apart in order to widen his base of support.  Because the receiver lowered his center of gravity and widened his base of support he was very difficult to push over and so was able to shrug of the tackle.
 There is now only one thing stopping the receiver from the end zone, a help side corner is running in really fast.  The receiver knows that he cant outrun the corner, but he knows how he can use his speed against him.  Right before the corner is about to lay a big hit on  him, the receiver stops in his tracks and the corner goes flying past him.  The receiver knows that this is because the corners inertia kept him moving in his current state and resisted change in motion such as the receivers sudden stop.
Touchdown!! Everyone goes crazy! Well except for the guy carrying his drink up the stairs in the top tier bleachers, he missed it cause he was busy doing work.  As he was walking up the stairs he was was doing work on his drink as he was moving with a force and a distance that was parallel.  
All the players are loading the bus after the win and get ready to drive back.   The punter who happened to be a physics minor in college thinks its pretty cool how the motor in the bus or any other motor is really nothing more than just a current carrying wire that is experiencing a force in its magnetic field causing a torque and making it rotate.

                                                                          UNIT 7

Hey wanna know something that's really attractive?......  MAGNETS!!!!!    

Yup, were gonna talk about magnets today.  

A magnet is an object that has its domains aligned in the same direction.   Well what are domains? 

Great question, domains are caused when the electrons in a certain area spin in the same direction.                                                                                                                                                                          

                     Aligned Domains = magnetized          Unaligned Domains = Not magnetized 

                       

Because a magnet has its domains all in the same direction, a magnetic field with a specific direction is present in and around a magnet.   Inside the magnet the field flows from south to north.
 But outside the magnet the field begins to turn around and flow from north to south.
The symbol used for magnetic field is 'b'. 

                                

The Earth also has a magnetic field just like a magnet.  Except the only confusing this about this is that the earths geographic north, is the magnetic south.  That is just silly in my opinion, and i think that whoever named the geographic north and south owes us an apology.   

The magnetic fields on Earth are responsible for some of the most amazing natural phenomena called the Northern lights. The Earth is constantly being bombarded by cosmic rays.  And most of the time theses rays are deflected back into space my the Ezarths magnetic field because they are moving perpendicular to the field.  However, at the poles some of the rays are not deflected by the magnetic field and make it into the atmosphere.   This results in a beautiful light show.  

               Electromagnetic induction: Ok,  what is that?      Glad you asked.
Electromagnetic induction is when the magnetic field of a non current carrying wire is disrupted.   What this causes is a change in voltage and potential energy which induces a current.  
This is a principle that we see everywhere.  At stoplights, credit card machines and metal detectors to name a few.

                        

All of this is based off of Michael Faradays's Law which tells us that when a magnetic field changes a voltage is caused.  And this discovery is the reason why teenagers are able to bankrupt their parents with the swipe of a card.


                                                       Motors  vs. Generators
Motors and generators are very similar in that they both use magnets and coils of wire.  Where they differ is what they produce.

A motor takes electric energy and turns it into mechanical energy by using a current carrying wire to feel a force and generate a torque.   This torque can be used to turn anything form the wheels or an RC car, to a hand mixer.

A generator turns mechanical energy into electric energy by having magnets spin over coils of wire (or vice-versa).  This is able to generate electric energy because when a magnet passes by a coil it induces a current.   This is the basic principle that we get our daily electricity from.  


            But what do you do when there is either to much or to little voltage flowing to your device?
WOW,  you are just full of great questions today.    Well the answer to that question is something called transformers.   Transformers at its most basic level are two different stacks of coils with varying numbers of loops depending on whether it is a step up, or step down transformer.
 
                    
This one above is a step up transformer because there are more loops in the secondary coil than in the first.  This means that the secondary will have a higher voltage.  
But wait, how can they have a current of voltage or any of that stuff if they are not touching?
Wow I should give you a medal because you ask just the most relevant questions.  :)
Well the answer to your question my friend is induction.  By using AC current the primary wire induces a current in the secondary wire without even needing to touch it.  Cool huh?

                                                                             Unit 6

This unit is all about charges and electricity.  First lets talk about the most basic aspect of electricity, Charges.  

Charges:  Come in two types.  Negative - and positive +.  If something has more negative charges then that object is itself considered to be a negatively charged.  Likewise if an object has more positive charges it will be positively charged.  However, when there is a balance of + and - charges the object is considered neutral.   

One more curious aspect of charges is that like charges repel each other   -    -         +      +

and that opposite charges attract each other   -+     

       There are three ways that an object can obtain a charge.

1) Direct contact. This occurs when two objects have a point of contact and electrons are transferred.

2) Friction.  This occurs when two objects rub against each other and one object will steel electrons from the other.

3) Induction.  this occurs when objects do not touch, but the force is great enough that the charges move into the other object. 

     Another important charge related thing is polarization.                    Polarization is what occurs when the charges in an object move to opposite sides of an object.  What this results in is the object becomes charged because there is an imbalance between the -  and + charges  in the object.  

Coulomb's law:  F=kq1q2/d^2

Hey wanna hear something shocking?  ELECTRICITY!!!! 

But really electricity is pretty cool.  The way that we measure electricity is in Amps  A.
Electricity flows in circuits like the ones that we used in class to light the light bulbs. 

In the picture above the light bulb lights up because it is connected to a completed and unbroken circuit.  This allows electricity to flow to the bulb.  But hold up. Why does electricity flow?   

Well this all has to do with voltage.  When there is a difference in potential energy, a voltage is induced.  this results in the flow of electricity called current.   

                                     Voltage = V 

                                     Current = I 

Ok, so back to the circuits.  Circuits themselves come in two types, series and parallel.  

Series circuits have one path for current to flow.  This means that when one portion of the circuit is broken, the whole thing fails.  

   

Parallel circuits have multiple paths for the current o flow.  This is helpful because it means that when one part fails, the rest of it can keep going.   

In things such as buildings, where electricity needs to go to multiple places, parallel circuits are very useful in that they allow certain things to have no current, and others to have current. All while keeping a complete circuit. 

The wires that make up circuits have differences in thicknesses and lengths.  And what this causes is varying resistance, 

 

                                               Increased length/thickness = increased resistance. 

Resistance = R

 

                                        The formula for current: I =V/R