How the Earth was Formed

According to many scientists, the Earth was formed by a series of high speed collisions of smaller space matter which continually melded together (after collision). This created an extremely hot body of rock and as the collisions slowed down, the earth began to cool, which formed a small crust on its surface with a liquid molten material that formed the inner core. As it continued to cool, water vapor began to condense which allowed water to begin accumulating. Scientists believe volcanic activity and gasses which escaped from the inner layers of the earth formed the atmosphere of the earth and allowed for the eventual life on earth.

Homework due 11/20/2009 Air Bags

Because Newton’s first law of motion expresses that an object in motion will remain in motion at a constant speed in a straight line until acted upon by an outside force, when a car crashes, inertia will keep everything inside the car in motion at the speed that the car was travelling when a car crashes. While the momentum of the car stops immediately, the momentum of everything in the car (people included), carries the contents of the car forward even after the impact of the crash. Because of the close proximity of the driver and passenger to the dashboard/steering wheel and the great impulse (change in momentum) after the impact of the car crash, the job of the airbag is to prevent injury in a short amount of time. This means the airbag must counter the momentum of the people in the car to slow them before they are hurt by the impact. This is why the airbag inflates so quickly. It must absorb the momentum and slow the person down rather than allowing the person to hit the solid dashboard and risk likely injury.

Conclusion of Skateboard Experiment

Result:

1. 0.54 m/s = accelleration of the skateboard
2. Does not appear valid simply by reasoning/common sense

                                                              i.      Our accelleration shouldn’t exceed the kinematics equation result

                                                            ii.      Kinematics equation result: .47

                                                          iii.      Only a .7 m/s differnece but the fact that this is a + difference is an issue because there is nothing but human error that would increase the acceleration past that of the hypothetical world of kinematics which has no gravity or friction.

1.  
   1. Errors:

                                                              i.      Human error of stopwatches stopping at same time

                                                            ii.      Road error: ie. the road was not fully smooth, there were holes, and there was friction whereas the kinematics equation assumes a frictionless environment

1. Example of human error from results: the average velocity should not decrease at any point in the skateboard’s travel but the speed decreased by almost 2 meters per second between 10-12 meters.
2. Slope of hill may not be constant all the way down.

 The result acquired in this experiment was 0.5413 meters/second, which is about 0.7 m/s greater then the aceleration of the skateboard this is derived in the kinematics equation X_f = X_i + V_i t + (1/2)at² While these figures are fairly close (less than a 20% difference) and initially appear valid, the results indicate a prevalent margin of error on the part of those who performed the test and because of this, they are invalid. The kinematics equation indicates that the acceleration should only be .4747 m/s. It would be reasonable if the acceleration figure derived from the experiment was less than this acceleration, but it is unreasonable to have an experiment which yielded a greater acceleration than the equation did (as this experiment yielded). The kinematics equation does not consider friction that exists in the real world, nor does it account for the road’s imperfections (because it was not perfectly smooth), which would both result in a slowing of acceleration that should have occurred in the experiment. Because the results did not match the slowing of the acceleration that would be expected and instead reflected the opposite, it is clear that the human error in timing affected the results of the experiment, and thus the results are not valid.

             The human error that occurred must have had a large impact on the data collected and the acceleration that was determined for the skateboard, because this is the only reason the experiment’s acceleration would be greater than that from the kinematics equation. To fix this, a device which started the watches at the same instant and was able to accurately record the times at each mark would be required (such as a radar detector at each marking). Additionally, it would be easier to analyze the results if measurements had been taken more frequently, perhaps every meter instead of every 2 meters, so that the chance of outliers would decrease and the line of best fit for the velocity/time graph would better fit the points gathered. Because there is a possibility that the hill was not perfectly constant all the way down, and there was significant human error, the experiment would be improved by resolving these issues in a better-controlled, mechanically monitored environment.

Homework #9: Inertia and laws of motion

Assignment

1. Clearly define the concept of inertia, then give an example of a personal experience that you’ve had with:
i) the inertia of a moving object
ii) the inertia of an object at rest

Inertia is an object’s tendency to remain in motion when in motion and to remain at rest when at rest, based on the object’s mass.

i) Personal example: When I crashed my car, the car hit the wall at about 60 miles per hour, so when the car was stopped, my body was still moving at 60 mph forward and that is why I was pushed forward away from my seat.

ii) When a car runs out of gas, its very tough to get it started rolling towards the gas station, but once it begins rolling, inertia keeps it rolling and then moving it is much easier.

2. Does Newton’s First Law of Motion apply to large celestial objects such as the moon and sun? Explain.

Yes, Newton’s First Law of Motion applies to all matter so the moon and the sun stay in motion because there is no force that would stop them in space.

3. What is the concept of “net force”? Give an example in which the net force on an object is zero, as well as an example in which two forces act in different directions but do NOT add up to zero.

Net Force is when an object is effected by more than just one force. For example, when a rope is pulled at each end in a game of tug-o-war, if the teams are pulling with the same force of newtons on each end, the net force of the rope is zero. When one team pulls harder, for example if Team A pulls the rope with a  force of 5 Newtons to the right and Team B pulls with a force of 12 newtons to the left, the rope would be pulled to the left as the net force was 7 newtons left.

4. What is the state of motion for any object that is experiencing a net force of zero?

For any object that is experiencing a net force of zero, the state of motion is at rest, and until a force effects that object in some way, the object will stay at rest.

5. Explain how both your seat and your desk are providing support forces at this very instant….

Both the desk and the chair have a net force of zero because they are both being pulled towards the earth by gravity while simultaneously being pushed from the earth with equal force. At this moment, the chair and desk are providing me with upward support because while gravity pulls my weight down upon them, they push with an equal force up on me to create this equilibrium of net force at zero.

Homework #8 Force Carriers

Force Carriers are the particles which are exchanged in interactions between atoms and in this, cause force to occur. The four fundamental forces are Electromagnetic, Strong, Weak, and Gravity, and each of these forces has force carriers which cause them.

Assignment: Take notes on the ideas associated with force carriers, and then go to your blogs and write a paragraph in which you name the force carriers and identify the basic properties/actions/behaviors of each carrier. 

Photon: the force carrier particle for electromagnitism, which has no mass and always travels at the speed of light. It is the force of electromagnitism which keeps like-charged particles repelling eachother and opposite-charged particles attracting eachother. The photon travels at speeds which produce everything spanning from x-rays to radiowaves. These particles act on quarks and charged leptons and W+ and W-.

Gluons: “Glue the quarks together”. Essentially this is how scientists explain how the nucleus is held together because the strong force, which only interacts on the VERY small level, holds the quarks together in hadrons. Gluons (and quarks) are color-charged particles which, like the electrically charged particles, interact with eachother, but rather than having a positive and negative, they have blue, red and green charges. Because the quarks in a hadron exchange gluons ”madly”, scientists talk about the color force field, which is basically the gluons doing their job and holding the hadron together. *Note* Quarks absorb and emit gluons constantly. These particles act on quarks and other gluons.

W+, W-, and Z Particles: The particles which cause the weak interaction, which is responsible for the decay of “massive quarks and leptons into smaller quarks and leptons”. The W’s are charged while the Z particle is neutral. *Ken, the Electroweak force was a little confusing to me…* These particles only act on quarks and leptons, and they are heavy carriers, compared to the others which have no mass!

The Graviton: This particle, though it hasn’t yet been discovered, is suspected by scientists, to be the force carrier for the well known force, Gravity. This is the weakest force of the 4. These particles act on all particles.

*All force carrier particles are bosons which have a spin of 1.

Homework #7: Force Carriers

Physics is defined in the book as “what is, and what happens”, and essentially the authors explained force carriers as the particles which control “what happens”. They are the particles which transmit each of the four fundamental forces as they are exchanged during interaction. All force carriers are bosons, and they all have a spin of either one or two. They can be annihilated or created to any extent because there is no conservation law which prevents it. Each force, strong, weak, gravity and electromagnetic, has its own force carriers that go with it. To this point, scientists have discovered a limited number of force carriers, the graviton which scientists have yet to actually discover but believe exists (associated with gravity). The W-plus, W-minus and Z  particles have been discovered and are associated with the weak force and unlike the other 3 force carrier particles, have a large mass. The photon (light emmitter) is the force particle for the electromagnetic force. And finally, the strong force’s force particle is called the gluon, which, as we have learned, make up protons and neutrons and hold quarks together.

Homework 4: Taking Stock of Where We’re at…

My Contract:

I, Danielle LaRoy, promise that I will not write meaningless or unnecessary words simply to fill the space on the paper and make the assignment look better visually. I also promise that I will do my best to complete every homework assignment and remember there is a purpose to each reading and exercise. I vow that I will hold myself accountable for my own success or failure in the class and I will not give up even when the concepts are tough. Finally, I will not “play the game” when it comes to my writing, so I will not provide an answer that I think people (or Ken) wants to hear if I do not believe it fully myself.

What ideas are new to you? What ideas are most intriguing to you? How has your perception of the nature of matter changed since the first day of school? Finally, identify and record TWO as-of-yet unanswered questions that you’ve formulated (in regards to the nature of matter) since the beginning of the year.

The study of leptons and flavors and the quarks and gluons and all the particles smaller than protons and neutrons (with the exception of electrons). The ideas of radioactive decay are definitely still confusing to me although I guess they aren’t brand new because I had heard of them before this class. I really find the idea of matter being a fact of probability (another new idea to me) and the idea that out of random chance, quantum mechanics says your had could pass right through the desk. These latter two ideas really changed my perception of matter because I never thought of it as a probability issue… rather I thought of it as a fact of life that a ball, when dropped on a table, would 100%, no matter what, come back up. But now I’m not so sure. As far as questions go, I’m really still unsure of what an antiparticle is or antimatter in general… What is it, and what purpose does it serve? How do people know its there? what makes one particle a “particle” while another particle is an “antiparticle”?