Top Ten Whatchamacallits of Physics

So there's this thing.... it's the rate of change of velocity an object experiences but I just can  NOT remember the word for it.... it's umm.... whatchamacallit... Acceleration!!!!! That's it. Acceleration is measured in m/s^2 and its formula is a= change in V/t. Let's say that a ball increased its speed from 0 m/s to 10 m/s over 5 seconds of time. If we were trying to find the acceleration of the ball, what equation would we use? We would use a=change in V/t. Since the ball goes from 0 to 10 m/s, its change is 10-0 so 10 m/s. We plug this into the top quantity. Because this change occurs in 5 seconds, we plug in 5 for time. a=10/5. The acceleration of the ball is 2 m/s^2.

So there's a rope.... if you put a weight on the end of it, the rope may snap. In order to figure out if it would snap, and which side of the rope would cause it to snap, we have to use these things... they're kinda like labels, but not really. Dang-it why can't I remember?? They're um.. whatchamacallits... VECTORS!!

 

 

In order to determine which side is most likely to snap, we have to draw a line, labeled 'F-net up' pointing upward from the ball (the ball is the weight on the end of the rope). Then, we need to draw a line pointing downward from the weight labeled 'F-weight.' Using a ruler, draw a diagonal line using the F-net up arrow as your guide. Line the ruler up with the top of the arrow and draw a line pointing up to the right and then an arrow pointing up to the left (you can see this in the picture). P.s. make sure you label one side, Side 1 and the other Side 2 so that you have a reference point as to which side, if any, would most likely snap. Drawing a line across and up from the middle of the ball and up to the vector lines on both sides, you can see which side would most likely break. The side with the longer vector is the side that will most likely break due to the tension put on the rope. Vector's also help us understand why boxes go down a slope and a sled slides down a hill.

 

 

 

Well, if you want to go skydiving any time soon and receive extra credit in physics, you have to understand... um.... uh... well.. this is awkward.... what's it called? It explains why it is that a diver speeds up so fast for a long time and then eventually begins to have a steady pace. It's called um... whatchamacallit... air resistance!! Air resistance is the forces that are in opposition to the relative motion of an object through the air. There are 2 things that will increase the force of air resistance: Increase the speed and increase the surface area. The force of air resistance increases as a parson falls through the air because they are speeding up. When someone is falling, their acceleration decreases, velocity increases, and the net force decreases. An important rule about air resistance is that acceleration is directly proportional to force. This means that when acceleration decreases, so does the net force and when acceleration increases, so does the net force.

 

 

So there's this formula that defines why that if a car and truck crash, the same force is impacted on both vehicles. If only I could remember the dang formula... it's umm... it's... whatchamacallit? f=ma. We know that the mass of a big semi-truck will most likely be bigger than the force of a tiny Toyota Camry. When the truck with a larger mass runs into a tiny car, the truck causes the car to accelerate forwards. This acceleration is obviously greater than the truck's acceleration.

Truck --> f=Ma

Car --> f=mA

Both of these equations will equal out, causing the force to be the same for both vehicles.

 

 

So there are two different kinds of velocities. One type is defined by how many rotations it makes in a given amount of time. The other defines the distance it covers in the same amount of time... well... if only I could remember these names for the different velocities. Well, the first one covers rotations.. so that's um... whatchamacallit? Rotational velocity!! Now I just have to figure out the second... this one covers the distance in a given time. It's not rotational so it must be... whatchamacallit? Tangential Velocity!! Lets say there are two cylinders, one large and one small and they are connected by a chain. Since tangential velocity is the distance they cover in an amount of time, the small cylinder has to keep up with the bigger one. Because of this, they have the same tangential velocity. We can figure out which cylinder has a greater rotational velocity by finding out how bug the cylinders are. The smaller wheel has a greater rotational velocity because the smaller one has to spin more times to get to the same distance as the bigger one.

 

 

So there's this reason that physics describes as to why and how an athlete doesn't fall over easily. There's one main principle to it and if you aren't doing it, you have a much greater chance of falling over. This is called... um... really? I can't remember it? its.. ugh... whatchamacallit? Base of Support!!! An athlete is less likely to be pushed over when they keep their legs shoulder width apart because having your legs shoulder width apart creates a lower center of gravity which causes stability due to a wider base of support.

 

 

There's a formula that describes to us why a car takes a long time to fully stop. If only I could remember what it was... I remember it has 2 initials, a 1/2, a quantity squared... it's whatchamacallit... that's right! KE=1/2mv^2. Let's say a car is moving at some speed and requires 10 m to stop. How many meters will it take to stop if the speed of the car is tripled? We can solve this by just plugging in 3v and then using that information to find work.

KE= 1/2m(3v)^2

KE= 9(1/2mv^2)

Work=change in KE

f(d)=change in KE

f(9d) = 9(KE)

This would take 9 miles.

 

 

So there's this thing that helps us understand why a bird isn't harmed when standing on a wire, but they get harmed if they run into both wires on a power line... how is this possible? Something about connecting a... um... what do you call it? We use it everywhere we have electricity... what's it called? um... whatchamacallit... A CIRCUIT!! That's right!! If a bird were to fly through the wires and touch both wires with its wings, the bird would be completing the circuit. When both wings complete the circuit there is a large potential difference so the voltage is increased and this causes the bird to get electrocuted. If the bird just stood or ran into one wire, it would not be completing the circuit so it would be fine.

 

 

 There are only two  more things I have to remember. It's an equation we use to describe why things such as a charged piece of cling wrap is attracted to a ceramic bowl. It's an equation with lots of exponents and looks kinds difficult but as long as you know how to plug in numbers, you're okay! I should be pretty good with figuring out these things by now.... it's um.. whatchamacallit?... oh it's Columb's Law: F=k(q1q2/d^2). When a charged piece of cling wrap gets close to the bowl, the bowl polarizes. Positive charges in the bowl move toward the cling wrap and negative charges move away. The bowl is not charged, it is simply polarized due to the fact that opposite charges attract and like charges repel. Since the distance between the opposite attractive charges is less than the distance between the like, repulsive charges, the attractive force is greater than the repulsive force. This is because of Columb's Law F=k(q1q2/d^2). Because the attractive force is larger, the cling wrap is pulled toward the bowl.

 

 

Okay, one more thing. There's this problem I have, I can't figure out the physic's behind why exactly air bags protect us. I mean I know that the air bag is big and fluffy and it's better than smacking your head on a dashboard... but I just can't remember the formula's that go into figuring out why this happens.... this problem is a doozy because it requires 5 equations!! That's a lot to remember, hence my current problem..... I think that if I think hard enough I'll remember all 5 whatchamacallits!! Well, I believe the first equation is p=mv. I can figure out the second one because it's the same as the first: change in p = p(final) - p(initial). Because the change in p is always the same, this means the impulse is also the same. And oh yeah!! Impulse=f(change in p). With these equations, I am able to find out why airbags are so important!!

When a person sometimes has to make a rash decision to slam on their brakes, he or she would like to know that they have the best safety precautions. No matter how they slam on their brakes, they go from moving to not moving. Because of this, change in momentum is always the same.

p=mv

change in p = p(final) - p(initial)

Because the change in p is always the same, so is the impulse.

J=change in p

If a person had to slam on their brakes, they would want to have a small force on their body because the greater the force, the greater the injury. If there were no airbag, They would be stopped very quickly by the dashboard, making the force very large. A driver would prefer to have airbags because it would take longer for the person to stop moving, causing a smaller force.

J=F(change in p)

J=f(CHANGE IN P)

 

 

 

 

 

 

 

 

 

 



Turbine Blog

When told that we had to build a Wind Turbine, I was not happy. With only a week until exams and final work having to be turned in. I did not have time to worry about building a machine. Well, thanks to google and previously taught concepts, I was able to create a very successful wind turbine.

I knew that in order to get the turbine to display voltage, the amount of coils was crucial. In our machine, each coil had 200 turns, making 800 turns in all. This made the turbine spin very fast, as seen in the video below. The coils make a voltage and when the magnets are close to the coils, the domains line up.

The materials needed to make the turbine were:
water bottle
coil wires
disk magnets
square dowel
round dowel
LED
fender washer
screws
wood for the platform
glue

 

 

 

The water bottle was used to make the turbine spin and cause a voltage. In order for the bottle to form this design, we had to cut the bottle in half, cut out a template for the bottom and top of the battle. When this was done, we plunged a hole through the cardboard with a sharpened piece of a round dowel. This round dowel went from the top of the machine to the bottom. this caused the bottle to spin easily and not fall off of the frame. We made 4 coils, each of which had 200 turns. After these were glued down to a piece of cardboard, we used the fender washers and disk magnets to align with the coils to induce the voltage. To do this, we made sure that the poles of the magnets were all facing the same way. When we attached the loose ends of the coils to a LED, we saw that we had successfully created voltage.

 

In this project, I learned that in order to induce the voltage, we had to make more turns of wire. When the turbine was able to spin faster, the possibilities of the turbine being able to light a light are greater. Sadly, ours did not. I really enjoyed this project. I would do it again in a heart beat!!

 

Magnetic Blog Reflection

Why like poles repel and opposite poles attract.
When a N and N pole are put side to side, they repel because the fields are going in opposite direction so they are wanting to move away from each other. When you put a N and S pole together, they attract because the fields are going in the same direction and are trying to become one magnetized object.

What causes magnetic fields?
Moving charges

What causes the Northern Lights?
Cosmic rays feel the force of earth's magnetic field and pulls the rays toward the magnetic poles of earth and because they are so concentrated on these two areas, you can see the force which is the lights.

How a magnet is weakened
When its domains are jostled by heat and collision

How a compass works
There is a magnet in the compass and its domains line up with those of the earth's magnetic field so the arrow points to the direction of the poles.

How does a laptop charger work?
The charger is AC. It puts energy into a secondary cell by forcing an electric current through it.

How Ferromagnetic materials are magnetized
The domains are aligned

Domain
A group of atoms whose electrons are spinning in the same direction.

Cosmic Rays
Cosmic rays are concentrated on the poles as a result of the earth's magnetic field

How a magnet picks up a paper clip.
1- domains in a paper clip are random. (domain: a cluster of atoms whose electrons are spinning in the same direction).
2- The magnetic has a magnetic field
3- When the magnet is close to the paper clip, the domains of the paper clip align to match the magnetic field of the magnet.
4- The paper clip now has a N and S pole and the N pole is attracted to the S pole of the magnet so they stick together.

Moving charges
A  moving charge feels a force in a magnetic field.

Why do cosmic rays enter at the poles and not at the equator?
The moving charges feel a force from the magnetic field of the earth. this force causes them to spiral around the field lines and follow them into the poles.

How does a credit card machine work?
1- Magnetic strip
2- Code on strip
3- Reader has coils of wire that induce the voltage and current
4- Computer interprets electrical signals and converts them back to the code that's in the magnetic strip

Why do transformers not work with DC?
In order for a transformer to work, there needs to ne an alternating current so that the magnetic fields change. With DC there is only a direct current and the magnetic field would not alternate.

Transformer equations
pV/pT = sV/sT

Power (primary) = Power (secondary)

VI (primary) = VI (secondary)

Motor Blog

Each Specific part of a motor is vitally important in order for the motor to run.
The battery is used as a power source to help create mechanical energy.
The 2 paper clips are used to help carry a current through the battery all the way to both end of the coil.
The coil is the main part of the motor. The coil is the conductor. The inductor is based off of how many turns in the coil there are and if the coil surrounds an iron core.
The magnet provides a magnetic field in the motor

We scraped the armature of the coil a certain way because it determines the way the motor spins. If both sides of the coil were completely scraped, the motor would just teeter-totter the whole time instead of going in a full circle. We strip only one side on one side of the coil and the complete side of the other side of the coil so that when the motor wants to keep going back n forth, it won't let it, and it will keep going in one direction.

An electric current in a magnetic field will experience a force. The coil will experience forces going in the opposite way. The loops in the coil provide a torque and the magnetic field is produced by an electromagnet arrangement called the field coils. The pair of forces created, creates a torque to rotate the coils.

The motor could be used to power any small device. Because the Induction wont be very big, it probably wouldn't power a big device.