Unit blog magnets

This unit was about magnets. We began by learning about the anatomy of magnets. The source of all magnetism is moving charges. There is a north pole and south pole in a magnet and the magnetism flows from north to south and opposite poles attract. But the poles of earth are quite deceptive. The north pole on earth is actually the magnetic south pole, oh yeah and earth is a huge magnet. The magnetism of earth causes strange events like the northern lights. We then learned about forces on a magnetic field, we easily memorized the directions of forces, currents and magnetic fields using the right hand rule. We reinforces the concepts of forces on a magnetic field by creating a motor. We had a battery with a magnet, paper clips and a current carrying wire. We wanted to convert electrical power into mechanical energy. Here is the video of my motor

 

We were able to redirect the force upwards using the right hand rule and move the current carrying wire in rotation. The current moved side to side and the force moved up rotating the wire up. We then learned about electromagnetic induction. When a magnet runs through a coil of wires a current is induced. Traffic lights and credit card readers utilizes this. The cars a magnets and there are coiled wires connected to the light right by the stop. We reinforced this knowledge with our wind motor project.

The process of turning AC current into DC current is creating a generator. The number of coils can change the voltage put into the source. Decreasing the coils in the second set increases the voltage and vise versa, it's directly proportional. When the number of coils in the system are two different numbers that is making a transformer, this way only a certain voltage and current gets to an appliance for safety reasons.

Motor Blog

     In class today we were assigned to make a motor. And to create a motor you need a current carrying wire and magnet. So we created the current carrying wires out of iron wires and made them into loops. We shaved the top of each side of the wires to allow the current in from two common sources. We created a stand out of paperclips that we attached to the side of a battery with rubber bands. Then we put the magnet on the battery under the current carrying wire on the paperclips. The magnetic force was upwards and the normal force was straight and this force pushed the current loop causing a rotation. This is how we created a motor. The motor turned because we created a force to push it by adding current and magnetic force into the equation. This motor could be used to turn wheels on a mini car if we used thicker more sturdy wiring. Here is a video of my motor. 

Unit 6 Blog Post

In this unit we dived into how electrical systems worked and studied the behavior of charges. We started by demonstrating and everyday situation. We rubbed a balloon on somebody's head and stuck it to a wall. Electrons were taken from the head and added to the balloon which caused a negative charge. And we learned that opposite forces attract. So when putting the balloon on the wall the electrons began to pull on the positive protons on the wall and this caused polarization. The protons and electrons were attracted and were now moved towards where the balloon and wall met.
   We then went on to learn about charges and how they power everyday electrical appliances. In a wall outlet there is electric potential energy, the amount of electric potential energy is electric potential and the difference of electric potential energy is what creates current and this difference is called voltage.  My podcast was on electric potential/energy and capacitors and here it is




Voltage is measured in volts and out standard for outlets is 120v. The flowing of charges through a wire is called current and is measured in amps. Current goes from a electric potential energy source to a different electric potential energy place. The fluidity in which the current flows through is called resistance and is measured in Ohms. Resistance increases when the wire is longer, wider, or colder. Current is directly proportional to Voltage and indirectly proportional to resistance. Ohm's law represents this by saying I=V/R. There are two ways to wire things, series and parallel. Most appliances are wired in parallel because each appliance draws its own individual charge that way and if one burns out the others stay up, but because this draws more current the system will be hotter. To prevent over heating we use circuit breakers, these are switches that turn off when to much heat is drawn. These circuit breakers are wired in series so it cuts off the whole system when to much heat is drawn. Series is a wiring that has all appliances share the voltage causing less efficient running appliances and when one cuts off they all cut off. Coulomb's Law states k*q1*q2/d^2, which means the closer to objects are to each other the stronger the force they will feel.
In order to create current you can use induction (no touching), conduction(touching), or friction. The most confusing thing we learned this unit was electric fields. Electric fields are charged areas where outside charges become matched with an opposite charge without affecting the inside of the field. Here is a video explaining. https://www.youtube.com/watch?v=laGSICm_agM (No embed available).

Final Mousetrap Car Report

The mousetrap car like physics is a very frustrating. This annoying contraption somehow outlined almost everything we've learned so far in physics. This car used all of Newton's three laws. It used newton's 1st law in that and object in motion tends to stay in motion and an object at rest tends to stay at rest. This law applied to actually getting the car to move and to do this you needed a certain amount of friction to actually develop a movement and not too much friction because this would stop the car. To create friction we put tape on our wheels but only the back wheels cause too much friction would render the car's movement. Newton's 2nd law acceleration = force over mass or A=f/m. This meant that in order to accelerate more we needed to get a good force over a small mass. The smaller the mass the larger the easier it is to accelerate. In order to to this we tried to use light efficient materials. And lastly Newton's 3rd law, every action in an action reaction pair has an equal and opposite reaction. The wheel's push the ground back and the ground pushes the wheels forward. Avoiding centripetal force which did become a problem for Lincoln and I. The wheels were the biggest struggle for Lincoln and I that is because the wheels deal with the delicate balance of friction. We tried a variety of tapes to create friction but they were all too much, so too much friction was definitely a great disadvantage. We first started off with wood wheels that created to much friction so we switched to CDs, theses CDs created just enough friction to move and the right amount to keep moving. We had a pretty large force on our car so we used larger CDs in order to cover a good distance. This is because CDs are large and the diameter (lever arm) of the wheels increases the torque. However big wheels are harder to get spinning so we needed a lever arm to create enough force to spin the wheels and keep them going. When it comes to energy, the mouse trap car our potential energy came when we winded back the mouse trap and axel, but when we let the mouse trap do its work the energy becomes kinetic. Winding the axel more created more potential energy that would become more kinetic energy, this was very important to the function of our car. Because we tied rope to the axels we wanted to have more rotational velocity to compensate with our wheels. I knew that we needed to create a lot of rotational force to get these wheels moving to do this we created a lever arm as an attempt to increase the tangential velocity. This helped get our big wheels moving in order to increase the distance. Because the spring is going up and down and the car is going forward, these two forces are perpendicular therefore work can't be calculated. We can't calculate the potential energy in the spring because we can't calculate work. There is energy stored in the car ( potential) but when it begins to move it becomes kinetic.

 .83 m/s

     Reflection: Our original design featured a tapir wheel design big in the back small in the front and a mouse trap with strings attached to the axel. We initially had trouble with the cart because the axels had too much friction in it. To solve it I took the tap off the axels to where it went in the car and it worked wonders. Friction became my arch enemy during this project. Ugh I hate determining the right amount of friction to use our friction problems initially kept our car from moving. If I could redo this I would use lighter wood more glue and CDs would be my wheels from the beginning. I would also do more research to make the most efficient model ever, I would import my materials from abroad and grease my axels.

Unit 5 Blog Post

Unit 5 was a pretty equation heavy rather than conceptual. We first began by going over work. Work is force x distance, but the force and distance both have to be parallel or no work is being done, and the only distance used is vertical. We introduced work with a experiment in which we walked, and ran upstairs. The point of this exercise was to understand that no matter how fast you reach a fixed height you will be doing the same amount of work because work is simply force times distance. But when you added weights you changed the work because you changed the force you had to carry in that upward distance. In this experiment we were not just introduced to work but also power. Power is work over time. Meaning when we ran up the stairs we had different power than from when we walked. We actually had more power when we ran, this is because the time was less and when you divide the work over a smaller time you will have a larger result than a larger time. Power is measured in watts. Hmmm... Watts and Power? Sounds familiar. Oh yeah that is because when we hear power we think of horsepower. Horsepower is what they rate an engines strength and speed on. A single horsepower is 746 watts and when running up the stairs I was able to produce a full horsepower.
     Our next topic was Kinetic energy (KE) and it's relationship to work and Potential energy (PE). Kinetic energy is the energy and object has while in motion. Or work in motion. KE= 1/2mv^2. KE and work are related in that change in KE(or delta KE) = work. My podcast group chose this topic and here is our video for it...

Our video showed Luke's car changing velocities and therefore kinetic energies and their respective differences and then we found the distance it would require to stop by using the equation Change in KE= work. Because the velocity is the KE equation is squared the stopping distance will be squared. say you have a velocity of 2, your stopping distance would be 4, 3 would be 9 and so on. We used the stopping distance as our bread and butter in explaining the relationship between Kinetic Energy and Work. Potential energy is the energy that depends on an objects height. PE=mgh. An object will have high PE at a large height and zero PE on the ground. Another group in our class did a video on PE relationship with KE. 

They use a pendulum to describe the relationship between potential and kinetic energy. PE and KE are always conserved. The max energy will always be the su of KE and PE. A resting object at its peak will always have it's highest PE and lowest KE (0). At the bottom it will have its highest KE and lowest PE (0) and will reverse when it gets back to the peak.
    The last key concept we learned was machines. Machines help us by directing the work we do on an object more efficiently. To carry a 1N box 1m up we can't change the work done, but we can decrease the amount of force we put in. We can do this because work=f x d, and we can change the distance it takes us for us to get to the target distance. We can do this because if we are trying to get a box 1m high the only thing important to work is the force and upwards distance, but we can increase the horizontal distance up toward the vertical height we want to reach and fraction the force we exert. Ramps, Pulleys and levers are machines that do such things. By increasing the D in we are able to decrease the f in. This is how machines help us, not by decreasing work, but by making more efficient use of our force put in.

unit 4 blog post

I think unit 4 was my favorite physics lesson so far. Every lesson in physics is applicable to real life but I felt as this unit hit my areas of interest. We kicked of the unit by first going over torque. Torque at a mathematical level is force x lever arm. But scientifically torque is the tendency to rotate at an objects axis of rotation. You can increase torque on objects to help you achieve tasks as well. This video gives examples on how to... 

In class we had a mass of meter stick challenge in where we were assigned a meter stick with a 1 kg weight attached to it. To find the weight we had to find the center of mass of the meter stick without the weight attached. We accomplished this task by finding the torque on both sides of the meter stick while balancing it with the weight attached. 

All objects have a center of gravity/mass. We can manipulate the distribution of our mass to keep our center of gravity from rotating. In football linemen crouch with their legs far apart and knees bent. They do this and it makes them harder to rotate or be knocked over for two reasons. Spreading ones legs widens their base of support which gives more space for their weight to go over. An object looses balance when it's weight is not over its base of support. The bent knees keep a person's weight close to their axis of rotation and this keeps them closer to the ground and base of support which makes falling over more difficult. This video explains the application...

Objects rotating  have two velocities, tangential and rotational. Tangential velocity is the distance cover in a spin while rotational is the amount of spins over given time. We see these in gears. You can have tow gears connected, a small and large, and they will both have the same tangential speed but different rotational velocities. This is because they both spin the same amount of notches per second but the smaller gear finishes a rotation quicker. Th wheels of train tracks are tapered so they have varying rotational velocities and because the train spins on wheels, it is the rotational velocity that controls the speed and direction of the train.
     We also learned about rotational inertia. As an object spins, the distribution of it's mass can change it's rotational inertia. When an objects mass is closer to it's axis of rotation it has less rotational inertia and spins faster. This is how ice skaters are able to control the rate at which they rotate. My group video explains how rotational inertia works and how it is conserved.

The last thing we went over was centripetal force which literally means center seeking. This force is by the moon stays revolving around earth. Earths gravity acts as a rope pulling the moon toward it so the moon does crash off somewhere. Say you have a bucket of water and rope attached plate. You put the water on the plate and start to spin it around your head. The water does not spill because the centripetal force keeps it towards the middle of the cup.

Mass of Meter Stick

In class Monday we were assigned a meter stick with a weight strapped to the end. Every meter stick was a different weight and all we knew was the mass of the weight. The objective of the meter stick project was to find the weight of the meter stick just using the provided weight. Ali and I were grouped together and knew that the first peace of information to jot down was the center of gravity on the stick and the distance from the center of gravity and the end of the meter stick. This will be one of the lever arms. We can now find the torque, because torque= lever arm x force. The center of gravity was at 50 cm and the weight was 1 kg. To calculate force we multiply gravity by mass and we get .98. The meter stick with the weight balanced at 30 cm so the lever arm was 30 cm. Force .98 x Lever arm 20 cm, this will give you torque. And because the object is balanced  the torques on both sides must be equal. So .98 x 30 cm = the distance between the balancing point (50cm) and the center of gravity which was 20 cm. So .98 x 30 cm = 20 times lever arm (unknown x). When solving for x you get 1.47. So now you divide 1.47 by .98 and we got 145 grams. The actual weight measured on a scale was 150 grams. For future experiments to get more accurate results we could find a better table to measure the center of balance and more accurately measure center of gravity. This experiment  helped me by giving me a physical example of gravity and torque on objects. I know know how to use equations for torque to find the weight of objects.