Class on Monday, November 30

The first thing in class that we did was take a reassesment. Then we started talking about FARMIPS and grades and how to prepare for the exam.

We then talked about whether a bowling ball dropped from a foot above your hand or a baseball dropped from the top of robinson would hurt more if dropped on your hand. We decided that the pain and how much you'd get hurt relies on speed, mass, and height (if dropped). Then, we jumped from that subject onto springs. Let's say we have a very loose spring, and a very stiff spring. We asked ourselves "How can we launch the same cart with the same speed using these two different springs?" We made this graph of the spring force vs. the displacement:

The rest we did in class i didn't catch so we'll talk about it tomorrow! The next scribe is Joe.

Class on Tuesday

Today in class we discussed the article that we read for homework. We went over the topic of meta cognition, and a fixed mindset vs a growth mindset. A lady did an experiment that showed when they told a kid they were smart the kid opted to choose an easier test, and when someone was told that they were a hard worker they chose the harder test. For the rest of the class period we did a lab that reflected vpython, and we tried to experiment with it and learn how to use it. This class period was mostly experimental and we all went away with a basic understanding of vpython. The day before we took a major reasessment.

LHC is on!

THe LHC produced the first collisions of protons today.

Friday Nov. 20

On Friday we started by taking a chapter 4 reassessment. After we finished we got a blank copy of it and went over it. Next we broke into groups to solve a hard problem that Mr. Burk gave us. On the board Mr. Burk drew a block with mass, m. Attached to it was a spring that was angled upward at angle theta, had a stretch of change in r, and a spring constant, k. Our task was to solve for k in terms of m, theta, and the coefficient of friction. The problem was long, hard and tedious. It took a lot of steps, algebra, and combining different concepts we have learned but in the end we figured it out and I think everybody either got the answer or came within a step or two of it. Next we came back together and Mr. Burk solved the problem himself and went over the steps. After that we reviewed for our assessment on Monday. We started from 4.1 and went over each concept. That was pretty much what we did in class on Friday. Don't forget about the assessment Monday. Jason wanted to be the scribe for Monday.

what is the homework? (my email won't work and for some reason i can't type in the text box...)

Gamma Ray Satellite may have found dark matter

Here's another great post that describes a recent discovery of what may be dark matter, which makes up 20% of our universe (regular matter is only 4%).

The excess gamma rays could possibly be coming from a hypothesized dark matter called Weakly Interacting Massive Particles (WIMPs), colliding with one another and annihilating themselves into pure energy.

Fermi may have spotted dark matter.

Want to conquer stress? Exercise is key

Here's a great article from the NYT about a new study on rats showing that exercise allows our brains to better handle stress.

Here's a quote:

It looks more and more like the positive stress of exercise prepares cells and structures and pathways within the brain so that they’re more equipped to handle stress in other forms,” says Michael Hopkins, a graduate student affiliated with the Neurobiology of Learning and Memory Laboratory at Dartmouth, who has been studying how exercise differently affects thinking and emotion. “It’s pretty amazing, really, that you can get this translation from the realm of purely physical stresses to the realm of psychological stressors.

solution to conical pendulum

here's the link, via posterous. If this doesn't work, I've also posted it to the calendar.

http://john-pyicv.posterous.com/

Posterous: another super cool tool!

Have you ever wanted to share a file, mp3, photo, or video without having to email everyone, or post an elaborate facebook status? Perhaps you have some great notes you want to share on the blog.

Well, here's the solution.

Just send an email to post@posterous.com, and attach whatever it is you want to share. Posterous will send you a link to the website you created with that attachment.

It couldn't be easier.

Jujitsu Time

First off we went through simple harmonic motion and the simpleness of deriving it's formula.
Now All Questions are supposed to be answered. How does this relate to the pendulum?


@= Theta for the purposes of this

Also on Centripetal Motion:
4π^2r/T^2=a=v^2/R

We can Determine that 2π*Square Root of (L/G) = 2π*Square root of (M/K) = T.

We use the following

Determining Simple Harmonic Motion over a Pendulum
Things we can assume:
Ay=O (Basically it's not moving up and down.)
Cos@ =1 (There is minimal movement of the pendulum so the cosine of the degrees is very close to 1 because the degrees movement is really small).

The Jujitsu Way to Own a Simple Pendulum problem in the face.
Step 1, Brick Breaker Create a Free Body Diagram
Step 2, Follow-Up Punch Find the net force (add up all your forces (using cosine
Step 3, See the Shadows: Find the Net force Fnet=<-Ft sin@, Ft cos@ - mg>
Step 4, Headbutt: Fnet= ma a=

Interlude, Break Period: Sin@=X/L

Step 5, Sweep the leg: Analayze Components y FtCos@ -mg = m*ay
Ft-mg=0
FT=mg
Step 6, Sweep the other leg: X:=-Fsin@=ma of x
Step 7, Wax on: Insert sin@ = X/L, -Ft x/l =MAX
Step 8, Wax off: Insert Ft=Mg
(-mgx)/L= MaX

Gather your thoughts: -Mg/L*x=Max
M's cancel out in the equation above ^.
-g/L x = ax

Step 9, Go for the crane kick: Look at the Force
-mg/L*x = max
Constant (k) = -MG/L
Linear Resting Force F=-Kxo
T=2π*Square Root of (M/K)
T= 2π*Square Root of (M/Mg/L)
T= 2π*Square Root of (L/G)

Homework is to do the hardest problem ever AND make sure you turn in Homework 4H. Next Scribe is whomever. Volunteer in class on Friday.... jk it's Sana.

great career advice from the creator of dilbert

Scott Adams, the creator of Dilbert, has a wonderful post on his blog with some great career advice.

Here's a quote:

If you want an average successful life, it doesn’t take much planning. Just stay out of trouble, go to school, and apply for jobs you might like. But if you want something extraordinary, you have two paths:

1. Become the best at one specific thing.

2. Become very good (top 25%) at two or more things.

The first strategy is difficult to the point of near impossibility. Few people will ever play in the NBA or make a platinum album. I don’t recommend anyone even try.

The second strategy is fairly easy. Everyone has at least a few areas in which they could be in the top 25% with some effort. In my case, I can draw better than most people, but I’m hardly an artist. And I’m not any funnier than the average standup comedian who never makes it big, but I’m funnier than most people. The magic is that few people can draw well and write jokes. It’s the combination of the two that makes what I do so rare. And when you add in my business background, suddenly I had a topic that few cartoonists could hope to understand without living it.

Suddenly, becoming extraodinary doesn't sound so hard.

2nd half of November 17, 2009

Today, for the second half of class, we discussed simple harmonic motion. This is produced by a linear restoring force. The restoring force is equal to the negative slope times the displacement or stretch. the velocity is never constant during simple harmonic motion and the velocity equals zero at the maximum displacement.

Then, we saw a weight hanging from a string move like a pendulum. We observed it moving back and forth and then in a circular direction. We timed the period of each. we then divided up into groups and found the length for one and the gravitational force for the other.

Tonight's homework is to finish 4H if you havent already or to work on the class lab. It was also recommended to read chapter 4. Mary Elizabeth can pick tomorrow's scribe.

Monday Scribe Post

So today we took a reassessment during class and got a sheet that had our overall reassessment grades. We talked about simple harmonic motion and watched a movie about it, where we saw the x and y components, but I never fully understood it. Simple harmonic motion has to do with spinning objects and squiggle graphs because that is what we saw in the movie. This is the type of motion that we saw::
http://en.wikipedia.org/wiki/File:Simple_harmonic_motion_animation.gif#filelinks
We also talked about the graphs that were for homework. C2 vs. C1 fully confused the class and I will try my best to explain the little bit that I understood. C2 is the constant/slope for the Air resistance vs. Terminal Velocity Squared graph and C1 is the constant/slope for the normal Air resistance vs. Terminal Velocity graph. So basically C2 is Fair/Vterm^2 and C1 is Fair/Vterm. C2 is a lot bigger than C1 when normal sized objects are involved, but with microscopic objects C1 is a lot bigger. That was monday.... and i dont really know who hasnt scribed but i dont think eliza has so... ELIZA!! :)

If you want to know more about drag forces

Wikipedia is a great place to start...

the physics of soccer balls

Now that you've learned about drag forces and projectile motion, you can put your skills to use and read about the trajectories of soccer balls. You'll probably find some of the notation in this article a bit overwhelming, but if you work slowly through it, and ask questions, you can get a lot from reading this article.

Trajectory Analysis of a Soccer Ball

Class on Friday Nov. 13th

The first thing we did in class on Friday was talk a little bit about projectile motion. Next we started discussing air resistance (also known as drag force). To demonstrate the effects of air resistance, Mr. Burk had a tube with air in it that contained both a feather and a penny. When he turned the tube upside down the penny fell downward much faster then the feather. Also the penny accelerated while the feather seemed to fall at constant velocity. In order to explain this we thought about the forces acting on the objects as well as the factors that affect air resistance. The only two forces acting on the objects are the gravitational force of the earth and the force of air resistance. The two factors that affect air resistance that we focused on were cross-sectional area and velocity. Since the penny weighs much more than the feather it has a much greater gravitational force. But the penny also has a significantly smaller cross-sectional area then the feather. Cross-sectional area is half of the normal area. We use cross-sectional area because air resistance does not act on the top of the objects. Since the feather falls at constant velocity it's air resistance must equal the gravitational force. When the force of air resistance and the gravitational force are equal it is called terminal velocity. This explains why the feather falls at constant velocity and why the penny falls with an acceleration of a little less than 9.8 m/s^2.

Next we talked about the physics of skydiving:

1. When a skydiver first jumps out of a plane his initial velocity is zero.

2. When he starts falling his velocity is about 10 m/s.

3. He keeps falling at an acceleration of 9.8 m/s^2 until he reaches a terminal velocity of about 200 mi/hr. His acceleration is 0.

4. When he opens his chute his acceleration becomes negative because the force of air resistance is greater than the force of gravity.

5. As his velocity decreases so does the force of air resistance acting on him.

6. As he nears the ground he reaches a new terminal velocity of about 5 mi/hr.

After that we went back to the tube. This time Mr. Burk used a vacuum to suck all of the air out of the tube. With no more air resistance when Mr. Burk turned the tube upside down the feather and the penny fell at the same rate. When he let the air back the feather shot up to the top of the tube because the air was traveling at roughly the speed of sound. Next we watched a video of a feather a hammer being dropped simultaneously on the moon. The feather and the hammer fell at the same rate but they fell very slowly because gravity on the moon is much smaller than on earth.

At the end of class we did a lab. We dropped coffee filters and used the motion sensor to track their terminal velocities. We started by dropping one coffee filter and then we did two, three etc. all the way to seven. We calculated air resistance by finding the mass of the filters and then finding the gravitational force. At terminal velocity air resistance is equal to the gravitational force. We did this lab to determine the effect of air resistance on velocity.

Hw was to graph f(drag) vs velocity as well as to linearize it.

I think Margaret wanted to be the scribe for Monday.

FAILCON: a conference dedicated to failing

It turns out that in the business world, just like the rest of like, of the of keys to great success is failing often and learning from one's mistakes. It can literally be worth billions. Good thing they now have a conference to teach you how...

Monday November 9th

In class today we went over the last question of 4G where the most important part of the problem was finding the x velocity component. Once this velocity was found, we could use the equation v=x/t. We knew the change in position was 56.6 m so we multiplied that by the velocity and got the time. We learned that a similar format could be used when finding the change in displacement with a gun fired at 45 degrees. The ladder part of class we worked in groups to write a good explanation to find the displacement at 45 degrees. The next scribe is Alexis

Reading graphs can get you on the national news

Remember Mr. Meyer? The math teacher who figured out that the express line isn't express at all? Well, he just got featured on Good Morning America.

A question: how do salad spinners work

You've probably seen a salad spinner before. Somehow, when it spins all the water leaves the lettuce. Washing machines do this too, and modern washing machines that spin in excess of 1000 RPM do an amazing job of getting almost all of the water out of your clothes before you even put them in the dryer.

Anyone care to take a stab at explaining how this works? You should try to explain this both from the inertia perspective (when you are outside the salad spinner/washer), and the non-inertial perspective (when you are inside the spinner, on a piece of lettuce, and subject to fictitious forces.

What is the best study break? Taking a walk in the woods

Scientists are interested in all sorts of questions, including "what is the best study break." Here's a study that tested how taking a short walk as a break from studying affected student's ability to memorize a series of numbers. It turns out that taking a walk in the woods significantly boosted student's memory compared to those who took a walk along city streets, or did not take a break at all.

What is the best way to take a study break?

Class on Tuesday

Class on Tuesday:

In class on tuesday we went over a lot of new things. First off my scanner hasn't been working, and I can't get an pictures of my notes up, so sorry about that. To go onm we went into a lot of detail about components and ended up figuring out that tan of theta = v^2 over gR. Then Mr. Burk had a turntable and set a ruler with three strings of the same length with a ball on the end. They were all identical except that each one went a little bit further from the center(radius of each one got longer). We had to predict what would hajppen when they rotated. We found out that the farther the ball was from the radius the closer to horizontal it got. Then Mr. Burk dropped a ball bearing and shot a ball bearing from a pinball machine like contraption and they hit the ground at the exact same time. This is because the horizontal velocity doesn't affect the vertical velocity. And since they both started with an initial horizontal velocity of 0 then they hit the ground at the same time. Then we proceeded to start watching/analyzing a mythbusters on whether if you drop a bullet and fire one from the same height, will they hit the ground after the same amount of time. We took many notes on this and with the data they gave us we could calculate really cool and complicated stuff.

The next scribe is Joe . . . he already made the post . . . I think Paxton is scribe for Friday.

The physics of free throw shooting

Now that basketball season is here, it's a good thing that physicists have worked out the best way to shoot a free throw.

See here: The physics of free throw shooting

Some tips from the article:

First, the engineers say that shooters should launch the shot with about three hertz of back spin. That translates to the ball making three complete backspinning revolutions before reaching the hoop. Back spin deadens the ball when it bounces off the rim or backboard, the engineers assert, giving the ball a better chance of settling through the net.
Where to aim? Tran and Silverberg say you should aim for the back of the rim, leaving close to 5 centimeters - about 2 inches - between the ball and the back of the rim. According to the simulations, aiming for the center of the basket decreases the probabilities of a successful shot by almost 3 percent.

The engineers say that the ball should be launched at 52 degrees to the horizontal. If you don’t have a protractor in your jersey, that means that the shot should, at the highest point in its arc to the basket, be less than 2 inches below the top of the backboard.
Free-throw shooters should also release the ball as high above the ground as possible, without adversely affecting the consistency of the shot; release the ball so it follows the imaginary line joining the player and the basket; and release the ball with a smooth body motion to get a consistent release speed.

“Our recommendations might make even the worst free-throw shooters - you know who you are, Shaquille O’Neal and Ben Wallace - break 60 percent from the free-throw line,” Silverberg says with tongue firmly in cheek. “A little bit of physics and a lot of practice can make everyone a better shooter from the free-throw line.”

Wedensday November 4, 2009

First Mr. Burk told us that we needed to be doing our self assessment and our reassessment that he gave us last week. Then he gave us our tests back with our corrections graded. Then we continued working on the lab where we analyzed the Mythbusters' efforts to determine whether a dropped bullet and a fired bullet would hit the ground simultaneously. They did, which makes sense, because vertical force, velocity or acceleration is independent from any horizontal force, velocity or acceleration. I couldn't find a video of this on the internet. We calculated the velocity of the bullets and the time it would take for them to fall to the ground, using velocity versus time graphs and the equations , and . Our homework is to do 4G and make sure that it is right, because Mr. Burk will grade for correctness. The next scribe is Paxton

if you have no data

This will help you...

Question About the graphs

Ok I get that we are supposed to make a Tension Force v Time graph but then how do we account for the other variables we changed like string length and mass size. because like we did 1 trial with 10g with tension force of 1.5 and string length 70 cm and got 3.74. However we did a trial with 1 g with tension force 1.5 and string length 30 cm and got 2.25. According to the graph those should be the same but they are not...?

can somebody please email me data from the lab on friday since I was not there.

thanks a lot, Dylan