Unit 7

Magnetism
Magnetism is caused by charges that are moving in all random directions when they are not magentized. They are sometimes in clusters we know as Domains. In a Domain, the electrons are all spinning the same way. They do not have an overall net direction until they are magnetized and then they align to match the magnetic field so that the charges in that field can continue to flow through.

Electromagnetic induction


transformers


power


generator


motor

generator effect


motor effect

10 ways we see physics!!!

We learned in physics about how magnets turn wind turbines. That coils are placed around magnets and when the wind blows the shaft turns the magnets over the coils to create a magnetic field to keep the wings on the turbine to keep moving.






Magnets, we learned in physics, have a magnetic field caused by polarity and charges moving all around. We know that the source of all magnetism is moving charges. Domains of other metal objects align with that of the magnet and stick to it.




As we learned, physics can even be applied to tides and the way the earth moves. We know that the distance from the sun  and that difference between the two opposing sides of the earth is the true reason that tides occur. Its not necessarily the moon that causes the tides.



Water has polarity to. This is physics applied in water. See how it sticks together? Its cool to see how the lack of gravity affects water. Space physics is pretty interesting!


Astrophysics! Another way of looking at space through gravity and physics. Remember how learned that gravity acting on you = weight, which  is less on top of a mountain, and that your weight is really just your distance from the center of the earth? Well gravity has an even more important role in space.



Momentum is an element of physics and even exists in swimming and water. Momentum is actually inertia in motion.


We can even find Newtons 1st 2nd and 3rd laws in music!!!!



This video shows how movies defy Newtons laws and the basic rules of physics.



This is an example of free fall in physics.


This video shows how video games and movies create realistic ways of abiding by Newton's laws and laws of motion in physics.

Current

Currents- The flow of charges through an object. It is measured in amperes. There are two types. Direct current and Alternating Current. We use both in society.
DC- Direct Current. (Charges only flow in one direction) hint: used in batteries.
AC- Alternating Current (charges flow and change in opposite directions). We manipulate Alternating Current by alternating the polarity of the voltage. AC is used in common household appliances.

Unit 6

Electricity and how we use it

Current

Conductor

Insulator


There are three ways to charge an object:

Induction- A charged object moves toward a neutral object. The like charges in both objects repel and so these charges in the neutral object separate and are polarized. The opposite charges in both objects move closer together and need to find the path of least resistance to eachother. The object is thus polarized and charged.
Friction- objects rub together to make charge. "electrons are borrowed"

Direct contact- things give eachother charge by touching directly

There are positive and negative charges. Electrons are negative and Protons are positive. Say an object has more of on or the other, then the one that it has most is the overall charge of the object. Negative charges repel eachother and positive charges repel eachother. But negative and positive charges attract.

Scientists are not so sure what causes lighting. But they do know how it works. Lighting is just a giant version of Induction. The clouds have charges and the ground has charges. Positive charges attract the negative charges in the ground. The cloud and ground are polarized and the like charges need to find the path of least resistance to the ground. The charges then "jump" accross the space- creating a flash of electric current called lighting. Lightning rods on houses help the lighting find the path of least resistance (because the rods are straight and are directly connected to the ground) so that the lighting will not pass through the house or building but will pass through the rod instead.

Coulombs law- distance is inversely proportional to the force between objects F= K q1 q2/ d squared



electric feilds
E= F/q
We usually talk about how the positive charges effect this field
Arrows show us how the field will affect a positive charge. Inward arrows say that the feild is negatively charged and outward arrows say that the feild is positively charged. Arrows that are far from the center of the field or that are farther apart from eachother show a weak field.

Voltage- The electric potential energy difference.  (difference between two points). (measured in volts).We also use it to measure how much energy is available out of one Coulumb of charge.
If there is a large difference in charge, then there is a large difference in potential energy. Which means that there is a large difference in Kinetic Energy since PE=KE.
V= change in PE/ q

Ohms law-shows the relationship between voltage and current through the use of resistance.

Resistance is a force that slows down the current and makes it weaker. If the voltage is stronger then the current is stronger, which would mean that the resistance is lower. Resistance is inversely proportional to current and voltage. Voltage and Current are directly proportional to eachother. The equation is I= V/R.
Ways of manipulating resistance: To make it more resitance -->
 Lengthen the filament in the light bulb or make it a thinner filament. Resistance is also measured in ohms.

Currents- The flow of charges through an object. It is measured in amperes. There are two types. Direct current and Alternating Current. We use both in society.
DC- Direct Current. (Charges only flow in one direction) hint: used in batteries.
AC- Alternating Current (charges flow and change in opposite directions). We manipulate Alternating Current by alternating the polarity of the voltage. AC is used in common household appliances.

Capacitors- smooth out the current that is used. They have electrically charged plates that build up electric charge by passing electrons between them.
Electric Power- the rate in which electric energy can be converted
Power= energy/time
Power-= current times voltage
series and parallel circuits are used in electric power. Series is just one loop while Parallel has two loops of cuircuits connected to eachother. We learned that if we added more appliances to a series circuit, the resistance would increase and so we dont use series if we are  in need of the use of multiple appliances. Now Parallel works just the opposite: as we increase appliances, current increases and therefore voltage increases. And because they are inversely proportional to resistance: resistance decreases.

Fuses- When the current becomes too hot, a fuse melts and stops the current from blowing a circuit and prevents the circuit from turning into an electrical fire. The fuse can be inserted anywhere within a series circuit but must be inserted into the series part of the parallel circuit in order to be able to block dangerous heat from causing a fire in the parallel circuit.


This unit, at first, proved pretty difficult.  I had trouble on the test and some difficulty understanding what was being asked of me in the quizes. Homework seemed a bit confusing as well. But when I took the time to understand it and write a blog post- I found it pretty straight forward. Thanks Mr. Rue!

Wind Turbines

Wind Turbines are pretty cool. The wind turns their wings which turns into mechanical energy that in turn turns into electrical energy. When the flaps turn, the simple generator inside turns the mechanical energy into eletrical energy. The simple generator is made up of alternating magnets that create a magnetic field. When they are moved because of the wind, it shifts the magnetic field over copper coils. Change in the magnetic field induces voltage that is sent through the copper wires to create electric energy.

Materials:

2 pvc pipes
2 wooden poles
cardboard
2 wooden circular objects
copper wire
small magnets
tape
glue


First we cut the cardboard into ceiling fan shaped flaps. Then we cut one of the poles into 3 equally lengthed rods. We cut one end of each rod in half and Then glued the cardboard flaps at an angle onto each rod. Thn we drilled each rode into the same wooden circle with screws. We then drilled a hole into the wooden circle that would perfectly fit the other rod that is the shaft.  Then we attached the pvc pipe to a connector of sorts after we had cut the pvc pipe to size. We used the cardboard to carve out two circlular pieces that would fit on both sides of the connector that forms the head of the wind turbine. Then we took 4 magnets and glued them opposite eachother on the sides of the other wooden circle. We drilled a hole in the middle of this circle to also match the shaft. We inserted this circle on the other side of the shaft opposite the side where the wings were glued.  Now we had to make the coil. We used pvc pipe to form the ideal size of the coil. We wrapped the copper wire around the pvc pipe over and over until we formed a thick coil. We placed the coil in the throat of the pvc pipe where it connects to the head. We ran the coil  wire down the pipe and wrapped the wire around the pvc pipe so that it would stay. Then we took the shaft and ran it through the connector head and fit the two circular cardboard peices on the end and used tape to seal it. The magnets were situated right over the coil. We put the wind turbine up to the fan and it produced as much as 1.9 voltage!


Good tips:
Alternate the polarity of your magnets so that they may induce a current
Wrap your coil as much as possible so that more current may be induced
The more you wrap it the thicker the coil and the more voltage you will have.
Try to keep the magnets from sticking together when you glue them to one of the circles (we had a little trouble with that)
Make sure to keep in mind that your coil must have two wires that stick out on both ends so that they can be attached to clamps that will measure the voltage produced.

 Yayyy! Go Physics and Wind Turbining Making!!!

Making the best motor in the world!!!!

Voltage

This video shows what a voltage regulator is! I thought it was so cool! Its important to know other ways in which we apply voltage to our world and how it is used.

Mouse Trap Car

speed of car= 6.65 seconds and 5th place

Newton's first law
object in motion stays in motion

                        Using one wheel  in the front helped us have less rotational inertia and less mass. The two wheels in the back are CDs covered with balloons. The CDs serve to lessen the mass as well. Bottle caps are glued to both sides of the cd to increase stability so that the car will stay straight.  The balloons serve as friction so that the car can move forward. The "body" is made of two slabs of the lightest wood we could find. To save mass, we chose to connect the mouse trap directly to the outside wooden frame. The axels are brass rods drilled through the wood. The front wheel was made up of two bottle caps and a wheel from a toy car. Paper was inserted inside the toy car wheel to make it have less friction against the brass rod. The bottle caps glued to both sides of the car wheel were originally used to keep the car wheel from tottering and therefore steering the car straight. The front wheel was not glued to the rod- so that it would freely spin. The back wheels were directly glued to the brass rod on the oustide of the wood, however the brass rod would still spin once the mouse trap was let go. We used fishing line, the strongest and smoothest material, to lesson the friction. We needed more tangential velocity so that when the string spins off of the back axel, it will travel faster-- so we added a glue stick with a drilled center and placed it in the middle of the brass rod. The easiest and lightest way to attach the fishing line to the rod was to staple it into the glue stick. We needed something that would hold fast to the rod and the glue stick worked perfectly. The lever arm was a pencil duck taped to the mouse trap. It  was light and therefore lessened the mass while also raising the tangential velocity so that the car would be able to cross the 5 meter mark.

Newton's first law states that objects in motion stay in motion unless acted upon by an outside force. This statement refers to the whole purpose of the car. We wanted to reduce the activity of outside forces on the car so that it would keep moving to pass the five meter mark. In order to do this, we lessened the friction in the front wheels as much as possible and avoided putting glue between the hole drilled in to the wood on the back of the car and the inside bottle cap holding the CDs in place. We had to glue the CDs on the rod without letting the glue leak from the bottle caps and touch the nearby wood where the axel needed to rotate. The holes drilled into the wood were drilled smoothly so that the brass axel would not catch them and therefore add friction to the system. However the front wheel served as a main problem. The car does need some friction, but it does not need much. The front wheel had glue on the sides where the bottle caps were attached, therefore making the ride a bumpy one and adding friction between the wheel and the floor.
Newton's third Law states that every action has an equal but opposite reaction. The back wheels would push down on the ground when the mouse trap is set off, however since the reaction is equal and opposite the ground must push on the wheels. So how does the car go anywhere? Its the same as the horse and buggy problem. The balloons are the hooves of the horse. They add friction so that the car may move. The two types of friction are static friction (only when the car is at rest) and kinetic friction (friction that the car has when moving). We need static friction so that the back wheels can stabilize and push down on the ground. However Kinetic friction must be avoided as much as possible.


The front wheels and the back wheels had different rotational inertia. However the tangential velocity was the same because they covered the same distance in the same amount of time. We needed the rotational inertia to be different so that the back wheels would have more and therefore create friction so that the car would be able to move forward. We wanted the front wheels to move freely  with less rotational inertia so that is why we chose smaller wheels.
The lever arm was the size of a normal pencil, probably six inches. The longer the lever arm, the higher the torque and the more output power there is. So when we first tried the car without a lever arm the car did not have alot of power. But by adding the lever arm we increased the torque and therefore the car went farther and had more power.

The less friction on the car the more conservation of momentum we have. That is why reducing the friction of the car is so important. Not all machines are very efficient, so if the mouse trap car is expelling sound, light, or heat... that is energy that the car has released and put into moving the car forward.

If we wanted to calculate the amount of work the spring does on the car, we would need to know the force. Since we dont know the force we cannot find the work and if we cannot find the work then we certainly cannot find the Kinetic energy the car used because work = change in KE. The change in KE is equal to the change in PE, Therefore we cannot find any of them. We cannot find the force in the first place because force = mass x gravity.. And we cannot measure the mass so therefore we cannot find the force.

Reflection:

We faced problems with the height of the front wheels, making sure that the axel is not crooked, and that the drilled holes are aligned. We faced problems with making sure the front wheel is stable. Adding bottle caps to all of the wheels was a deviation from the original design. But they were used for stability purposes and to create a way for the axel to rotate freely. I feel like the main problem was having foresight to find how to create the next step for the car. Another problem was the front wheels, we had to attach them several times and then that created friction so we ended up just letting them ride along next to the car tire and peeling off the glue. I would not want to do this project again; if I had to I would make things neater and I would use smaller wheels, less glue, and lighter wood.  

  

Unit 5

This unit is all about work, power, kinetic energy, machines, and potential energy and how they are all  related to each other.

Lets start with work.
Work is the transfer of energy.

Work = force x distance

Force and distance must be parallel to have work

If the force does not cause the object to move than there is no work done.

You are exerting a force on something for some distance

Work and energy are both measured in joules

Joules are actually just Newtons per meter. 

How is work related to power and Kinetic energy?

Work = change in Kinetic Energy

Power= work/time

When we did the lab, what we learned is that work = forcexdistance and that this distance is always the vertical height. When we walk up the stairs or we run up the stairs, we do the same amount of work as long as our weight (force) and the distance (height of the stairs) remains the same. Well why wouldn’t you be doing more work if you were running? Time has no factor in the work equation, so if you do the same thing in less time, the only thing you do more of is generate more power. And why is that? Power does have time factored into its equation. Power = work/time. The less time you have, the more power you generate.  Notice that the definition of power is how quickly work is done, so the reason the equation is work/time is self explanatory.

   

How is work related to Machines?

Work = F XD

(THIS IS AN EXAMPLE OF WHY THERE IS OR IS NOT ANY WORK DONE)

remember that because of this work is not force. 

the equation acts more like a balance when dealing with machines. Machines decrease the force and increase the distance. However: the work is always the same. If the work is the same then the kinetic energy is the same. If the kinetic energy is the same then the potential energy is the same in machines as before. 

Using machines:

You can never get more work out than the work you put in. However pay attention to the difference of "missing work" and putting and getting out work. Say that something requires a specific amount of work to be lifted and you have to put 20 more j of work in to lift it.. the missing work would be expelled as light, heat, or sound. This is why we hear engines and see light and engines are hot-> because they are not 100% efficient machines.  Remember that you can never get more work out than you can put it and that the numerator in a fraction is always smaller than the denominator= so that's why workout is divided by work in and work out is in the numerator position because it will always be smaller. 

Kinetic Energy is the energy of movement. Potential energy is the possible energy an object will have.

 Kinetic Energy= one half x m x vsquared

Potential Energy= Mass times gravity times height

Change in ke = change in pe

Potential energy is always at the top of a hill--- because its the energy that has not happened yet but could happen

Kinetic energy is the energy of movement, the energy at the bottom of the hill because it has moved. 

When we swing, the starting point and ending points are the potential energy while the very bottom middle is kinetic energy and the lines dividing the middle and both of the end points are pe= ke 

Work and Power

This image stands for "work".
If we wanted to know how much work the person is doing on that pile, we would need to know how far the person is travelling in total and then the force of their shovel because work= force x distance.

Say he has to distribute whatever he is shoveling 2 meters away and he makes 5 trips. So 2x5= 10 meters. Say that each shoveling needs 2N.  So 2x 5= 10n. So 10x10 equals 100 jouels of work.

Well to calculate power, we use work/time. So if he shovels for 20 minutes then 100/20 = 5 watts.

Unit Blog 4

This unit we learned about Torque, center of gravity, base of support, rotational inertia (more and less), angular momentum, tangential velocity, rotational velocity, centripetal and centrifugal forces.

Tangential velocity and Rotational velocity
Tangential velocity deals with distance: so if you were on the inside of a merry-go-round you would have less tangential velocity than someone on the outside.
As for gears: gears have the same tangential velocity (because they cover the same distance per time) but different rotational velocity (because one has a different number of notches and it must work faster to cover the same amount of distance)

Rotational velocity deals with whether or not the two objects are connected with an axel.
Rotational velocity deals a lot with train wheels.

Train wheels "self-correct".  1) train wheels have the same rotational velocity because they are connected 2) The wheels are tapered so the thicker part of the wheel has a higher tangential velocity (meaning it is covering more distance per time than the thinner part). 3)The thicker side thus moves faster(linear velocity). 4) So the wheel on that side will curve inward and push the axel to the opposite side (self correct).

A carousel has the same rotational velocity since you are riding on the same wheel as the other
person


Rotational inertia is a little different than rotational velocity. Rotational inertia is an object's willingness to speed up or slow down as it is rotating. If you have more rotational inertia your velocity is slower. If you have less rotational inertia, your velocity is faster.

So if I were spinning on ice, and I had my arms farther away from my body, then I would spinning slower. If I pulled my arms in, I would spin faster. When my arms are out, my mass is more distributed and farther away from my rotational axis. I will have more rotational inertia and therefore my velocity is slower. When my arms are in I have less rotational inertia because more mass is closer to my rotational axis and therefore my velocity is faster.

This concept deals a lot with Angular Momentum and conserving it.
Angular momentum= rotational inertia x rotational velocity.
When my arms are spread, my rotational inertia is larger and my rotational velocity is smaller. (in the equation)
put an = sign in the middle to show that when I put my arms in, the equation is equal. On the other side of the equation its the rotational inertia that is smaller and my rotational velocity that is larger.



Lets talk about torques.
Torques cause rotation.
There are two things about torques: they must have a force and they must be perpendicular.
If you need a larger torque, you must increase the lever arm, increase the force, or both.

A long lever arm takes less force, and a small lever arm needs more force. So If you have a really tight bolt, you will want to use something longer to loosen it.
hint* in a system= torques must always be equal to balance. (however the forces or weight does not)

Remember the equation: Counterclockwise torque= clockwise torque

                                        Force x lever arm   =   Force x lever arm

                                        (plug stuff in)

               *don't forget to show math, and don't forget to have the units of measurement



If the object on the scale has N, then you already have the weight and you do not need to work to find it before using the torque equation.

If you cut a bat in half at the center of gravity: Will the thicker side weigh more?
Remember that a shorter lever arm will have a bigger force (weight) so whichever side has a shorter lever arm will weigh more.



Lets talk about your center of gravity:
Its the middle of the distribution of your mass.
You want your center of gravity to stay within your base of support: which is how far apart your feet are spread. If your center of gravity comes out of your base of support, then you will fall over, or you will be easier to push over.

Now we can talk about centripetal and centrifugal forces.
The answer to a problem will never be:
centrifulgal force
its not centrifulgal force
or anything dealing with centrifugal force because its not real.

Centripetal force is the inward force that pulls on an object that is rotating, or rounding a curve.
The force that pushes you sideways when the car rounds a corner doesn't exist. Its merely newton's 1st law- you just want to keep moving in the direction the car was previously moving.
If there is someone next to you and you think that you hit them, you didn't. They actually hit you.


That's all for Unit  4!

I really enjoyed this unit and had fun learning about it. I learned a lot and it made sense to me. Hopefully I will do well on the test!

torque

This movie is a metaphor for torques. If you watch it, you can draw the parallel from the meaning of the movie and how it applies to the definition of a torque. The movie's whole point is that you live in a world that is constantly moving or rotating, just like the idea of torques. Like the wheels on the bikes that the actors are riding, torques cause rotation.

Meter Stick

Trying to find the mass of a meter stick without using a scale has thus far proven to be quite a challenge. I know that the point is to find the lever arm of the other side of the meter stick, but I have not figured out how yet. Lauren and I took some measurements and did some calculations. One thing we did clarify is that the center of gravity is supposed to be at 50cm. So we werent sure how to approach the problem, however we knew that f=mxg... and if we could calculate g and therefore f.. then we can solve for the mass. Also an important thing that we needed to know was that the center of gravity was at 50cm and that both lever arms therefore were 25cm roughly.


Here are the steps that we came up with:

Use torque equation
Find the lever arm of the weight side
find torque
Torques must be equal
set equation equal to eachother
solve for force
force is weight
w=mg
solve for mass
you done :)

tip*  force x lever arm = force x lever arm
  

This video explains the laws of angular momentum and what it means. The guy explains that angular momentum is the inertia of rotation of a rotating or spinning object . We can think of wheels, or planets, or anything rotating around another object.

Angular momentum deals with direction and magnitude.