Here is an article (via Mr. Otis) that seems to suggest that Mark McGwire’s steroid use didn’t help his home run record as much as people think. It suggests that he had the right physics to be a record breaker regardless of his drug use.

In the lack of hard data, it is my personal belief that McGwire has a point in what he said in interviews this week: It seems to me unlikely that subtracting the steroid-added bat speed would have deprived him of many home runs.

Because of the enormous kinetic energy invested in the baseball when a big league pitcher throws a 90 mph fast ball, to hit a home run McGwire had to act not only with strength, but very fast, and very precisely. He has less than a quarter second to see the pitch, judge its speed and location, decide what to do, and then start to swing. The bat had to meet the ball within an eighth of an inch of dead center to avoid a foul ball, at precisely the right millisecond to generate the correct arc to send it out of the park. [full story]

Baaaa! I don’t buy it. If McGwire didn’t think the steroids would help, then why would he risk his career on an unproven chance? Just to look huge and neck-less? You can’t “physics” your way around cheating.

Your thoughts?

Here we will look at many areas of physics occurring in this car chase in Dallas.

First find the momentum of the truck:

1 kilogram = 2.20462262 pounds Mass of average pick-up truck: 7,300lbs.

Velocity of the car right before impact: 10.4 m/s

Momentum = mass x velocity

p = (7,300/2.20462261) x 10.4 m/s

p= 34,436 kg*m/s

As you see on the graph above, in the onset of the crash the truck is going 36mph (1 mph = 0.44704 m/s). The truck then proceeds to slow down rapidly at -31m/s/s, but only slows to 23mph right before contact. Then the collision only ended lasted 0.4 seconds, which caused a lot of damage as the energy from the truck was transferred rapidly to the near stationary car.

For our Engineering Design and Development class Becky Kloes, Michael Thunes, and I (Kyle Kellner) are trying to make a bow stabilizer that will use gyroscopic stabilization to help keep the bow steady as you aim it at whatever it is you are shooting at (be it for hunting or just target practice). For this project we must prove first that holding the bow steady was a problem. So what we did is (with permission from administration) brought a bow in and videotaped people pulling back and holding the bow (without an arrow) while aiming at a camera. We then took the film that we got, converted it to a digital copy (with a little difficulty) and analyzed it with LoggerPro. It took us almost a week to complete this process but we eventually did and were kind of surprised at the results.

Attached at the bottom are our two final graphs. The first has everyone’s data points on it. You can tell that there is a fairly large spread on the data. For the second graph what we did was use Logger Pro to find the average X and Y components of each person’s data and plotted those points on a graph. This is a slightly better representation of the graph because it shows that people are all over the place. Not just focused in one place. Overall the average movement was down and to the left. After we make our project we will do this same process again and be able to analyze the difference. We are hopping to have the points more concentrated on the origin when people are using our invention. The final picture attached at the bottom is a screen shot of us doing the video analysis on Logger Pro.

The Schedule:

• If you cannot take the final exam during your scheduled time, please review the schedule below before making arangements to make it up.
• You MUST make arrangements with me before the exam if you plan to take the exam outside your scheduled time

Semster One Finals Schedule (click to enlarge)

The Topics: (see class wiki also)

• One dimensional motion
• Two dimensional motion
• Newton’s Laws
• Momentum

The Format:

• 50 multiple choice questions
• You may not use notes, calculators and other aids during the exam

The Grade:

• the final exam is 15 percent of your semester grade
• The final exam will be graded on a curve

It isn’t necessarily a good thing to give physic students some extra time on their hands. After coolforcoulombs drew the comic above, we both thought that it would be a good idea to analyze the comic. That then started a 30 minute calculation fest of as many of the cumulative physics equations that we could think of. We found that this was actually quite a helpful way to study and learn, as visualizing scenarios makes it easier to apply the concepts that we learned. We also learned that falling one ton pianos hurt quite a bit.

Note: This post is both credit of coolforcoulombs and myself.

The main unit used for momentum has always been: kg*m/s

I believe there is no real reason for the momentum short letter to be “p”. I have spent a considerable amount of time on researching this and found nothing. Many websites say that, yt was traditionally the letter used and they cannot find the origins of the letter.

Also many physicists use another unit for momentum: Since impulse equals (F*t) = (m*v), you can simplify it by using the first term. In the metric system, that would be Newton∙seconds, N∙s. Further Research: UNC site

A star, billions of light years away, exploded near the constellation Cetus. The interesting thing is that it exploded 7 billion years ago and it was just discovered! The star, Y-155, is 200 times the mass of the sun. Our sun’s mass is 1.98892 x 10^30 kg. So, the mass of Y-155 would be about 3.97784 x 10^32 kg. Its creation of pairs of matter and anti-matter was due to the star’s extremely hot core and caused it to explode. The energy output that Y-155 creates is “100 billion times greater than the sun’s!” If this star was located in our Milky Way, “it would have knocked our socks off.” Myth Busters busted the statement “knock your socks off,” and concluded that if it ever happened, you wouldn’t be alive to tell the story. Therefore, if this star exploded in the Milky Way, we would all be dead!

The picture of a Supernova would not upload, so here is a link instead:  http://upload.wikimedia.org/wikipedia/commons/9/9a/Supernova.jpg

To read more:  http://www.sciencedaily.com/releases/2010/01/100104151933.htm

The life cycle of stars, containing many different phases, is one of the most complicated subjects that scientists are learning about and trying to understand.  All stars start their life from a cloud of gas that is made up of mainly hydrogen and helium with a few other elements thrown in there.  From there, the star becomes a protostar, which is basically a prototype of a star.  In this phase, the star begins to fuse hydrogen atoms to make helium atoms.  If the star gets hot enough, it will begin a long middle age phase, which is the star’s main sequence.  Once the star has a high enough helium content in its core, the core contracts and it releases energy in the form of gravity.  The star then expands, becoming a red giant or a supergiant depending on the mass of the star.  The last phase of a star’s life cycle includes, becoming a planetary nebula, if it is a low-mass star, and then it will become a white dwarf.  However, if the star is too massive, it will supernova and collapse into a neutron star, such as a pulsar.  If the core collapses completely, it will disappear and become a black hole.

Recently, scientists suggest that there is yet another phase that a star goes through before death.  This phase is called an electroweak star, which is suggested to occur between the neutron star and black hole stages.  As their source for energy, electroweak stars convert quarks into leptons.  This energy could possibly stop the star from collapsing into a black hole.  This is still only a theory, since it is extremely difficult to differentiate an electroweak star from an ordinary star, if one is ever detected.  To be able to be more accurate on this topic, scientists need to comprehend stars better than they already do.

Article Link: http://www.sciencedaily.com/releases/2009/12/091214131132.htm

Recently in class we have learned about Hooke’s Law. This law says that the force applied to an elastic object will be proportional to the length of the stretch.  It also says that if the object goes past its elastic limit, it will no longer return to its original shape. You can see this in work as you watch a slinky “walk” down the stairs. You tip the top of the slinky (applying force) and it falls to the next step. It then returns to its original state (straight up and down) for a moment before continuing its way down the steps. Because of the force of gravity, the slinky continues to walk down the steps.

For a helpful simulation of this law click here.

Trampolines have been a favorite summer pastime for kids, teens, and even adults for many years. This old-time favorite revolves around what we are learning about- the force and energy of the jumper. The more force the person pushes down on the trampoline with, the greater the height of their jump.

I was able to find an article that explained the physics behind trampolines a little bit more. It involves more than just force, however. Energy also needs to be taken into account. The equation E = KE + PE (total energy = kinetic energy + potential energy) can be used to find the energy of the jump. In your jump, you lose kinetic energy due to the velocity of your jump while gaining potential energy. So, if you jump with greater speed and force, you will have a larger jump.