DavidStack

Hahahahaha blog of the year right here, no doubt.

Looking at the stationary bike that my dad bought for my mom for too much money, I realized that all these bikes do is take a normal bike and add friction to it in order to give the feeling like you are actually riding a bike. The friction of some material on the bike tire requires work to overcome it, and since W=Fd, the work required is the frictional force times the distance traveled, so you burn however many calories the work you did is equivalent to. Therefore, you can create one of the machines yourself very cheaply. You can create a simple frame using 2x4's, making a base and two A frames that the bike frame can rest into. Then take whatever bike you use during the summer time and attach a cork or something of the sort to the back of the frame that can put pressure on the back wheel and shabam! You have a beautiful exercise bike for your living room like the one below.

Although I personally believe that the Nintendo 64 is the greatest game system ever, playing Mario Tennis and my understanding of physics has led me to realize that a big reason why "better" game systems have been created is the lack of realism in the physics world in games such as Mario Tennis. The game creators didn't exactly take momentum into account given the fact that the ball is only hit with 4 speeds with 4 shots - a top spin, a slice, a lob, and a smash. In the real game of tennis, players derive much of the speed on their shot from the speed of their opponents shot. By shortening their swing, they rely less on building power through their wind up and instead get power by redirecting the power of the shot they are returning. Thus, the ball speed often increases during the point as more and more momentum is redirected. In Mario Tennis, on the other hand, the button you press is the only thing that determines the ball speed - top spin shots do not increase in speed during points. All in all, even though Mario Tennis is extremely entertaining, physicists can see the clear lack of depth of understanding by the creators of momentum and the transfer of kinetic energy.

I was set that her left arm was out and she was always moving counter clockwise, but I now understand that she is actually moving in both directions. Needless to say, this brought about plenty of unnecessary frustration.

Oo no cookie for Charlie, the problem is still up for grabs. And it's cause you bake Liz - you've brought this upon yourself.

Yes, but barely. It was 10-8.

In my computers class we looked up mind teasers on mindcipher.com in order to improve our problem solving abilities, but problem solving is certainly applicable to physics and this question was relatively easy but got your brain working a little bit: You need to tell time for 30 seconds but all you have is a non homogenous rope (some parts burn faster than others) that you know burns for 60 seconds and a match. How do you tell time for 30 seconds? And if that one is too easy: It's said that a number N with 4 digits is a double-square number when it equals the sum of the squares of two numbers: one formed by the first two digits of N, in the order they appear in N and the other formed by the two last digits of N in the order they appear in N.For example, 1233 is a double-square number since 1233 = 12^2 + 33^2. Find another double-square number. Enjoy!

I recently played a very poor serving tennis match and sit here thinking about why my serve was and often is so inconsistent, realizing that it comes mostly from my toss. The racket should contact the ball when the hitting arm is fully extended, but I often toss the ball short and contact the ball while my arm is still bent. By hitting the ball at the highest possible point, I maximize power and accuracy - the ball is at its maximum potential energy so more kinetic energy results when it is converted, and a higher height above the net means that the ball can be hit at a greater range of angles and still land in the service box. With a higher toss I can improve the consistency and pop of my serve so that I'll be like this guy :glee: and not this guy :banghead).

Alright Charlie, I'm writing a cookie problem just for you. You might need to get the cookie from Liz, but I figured I'd write one since you said there haven't been enough. And continuing with the Disney theme, here goes: Mulan is curious about how current and magnetic field interact, so she inserts her charge filled sword (which temporarily acts like a wire) of length 1 m into a magnetic field of 2 T in the postitive i direction, creating a force a 2.5 N in the positive k direction. 1) What is the direction and magnitude of the current? 2) What is the funniest movie David has ever seen? (You need to answer this correctly in order to get the cookie.)

The brain is an incredible thing and is refered to as the world's smartest computer for a reason. I've recently grown to love muscle memory as it helped me greatly in performing in a musical this past weekend. Even though I would be in the middle of a dance number and completely forget the next part of the dance, my body would do the moves for me without me even thinking about it. This is because of muscle memory, as our bodies build neural pathways after doing a certain activity over and over again so that when presented in a situation, we naturally do what we've done so many times. Even though I would feel like I didn't know what to do, the procedual memory of doing certain moves on the stage on cue with certain music and lights led to me somehow almost always doing the right thing. I also just realized that this doesn't necessarily have to do with physics, but I still think it's a really cool topic, and now I can dance like this guy.

Many people do not enjoy plane rides because of the uncomfortable feeling of their ears popping as the plane rises. This has to do with air pressure, a concept that is not really covered in AP-C Physics but we did deal with last year and is certainly important in understanding the general physics around us. As the airplane increases in altitude, the air becomes less dense (since less air is being pushed down by gravity), leading to a decrease in air pressure. Because of this, the air trapped in your inner ear will cause your eardrums to push outward, causing a discomfort. To compensate for this, your body naturally allows some air from your inner ear to escape through the Eustachian tubes, two small channels that connect the inner ears to the throat, creating the "pop" of your ears. You likely had no interest in this, or you were already aware of why your ears pop, but thanks for reading anyways!

So, we've lasted half the year in Physics, and what better time than now to discuss how I'm feeling about this class? Ups: 1) Physics C and BC Calc go well together. As I learn more in one class, it helps me understand something better in the other class. 2) It's interesting to learn more real world physics, such as air drag and taking friction into account, instead of learning the mechanics of a perfect world that doesn't exist. 3) Doing the same topics as last year, like momentum and energy and kinematics, has helped me to gain a better understanding of those concepts. Downs: 1) Rotational mechanics makes energy and pulleys much more complicated. Before, it was very easy to find the kinetic energy of a ball rolling down a hill or the acceleration of an pulley with a massed string (when we were allowed to ignore things we no longer are allowed to ignore), but there are more components now. 2) I have to study. In Physics B, I could do little to no work prior to taking a test and still do very well, but that is not the case now. 3) Webassigns are longer and more difficult. Even though physics is definitely more challenging this year, I've made it this far with very few bumps and bruises, so the rest of the year can't be too bad (knock on wood). E and M here I come! I'd also like to give a shout out to Slim Shady/Mr. Jericho/Mr. Ditty - you've done a fabulous job looking important while Mr. Fullerton teaches, and we're really gonna miss you. Visit soon!

Two very good points. While friction is an easy thing to blog about, I doubt that reducing friction while writing equations is really the thing to be focused about.

I have always failed at writing down 50 equations in 4 minutes, both last year and this year, and I was never really sure why because I do know a good deal of equations. But as I think about it, I usually try to think of every little equation - getting me flustered and slowing me down - instead of focusing on the general equations that can help me figure out other equations. So, here's a simplified equation dump of equations that can lead you to most any equation we've learned in mechanics. F = ma K = .5mv^2 U = mgh p = mv J = F(delta)t = (delta)p W = Fx = (delta)K P = W/t U(s) = .5kx^2 F = -kx F(g) = (GMm)/r^2 F(f) = (mew)F(n) T = 2(pi)(m/k)^(1/2) -> for springs T = 2(pi)(l/g)^(1/2) -> for pendulum T = 1/f F© = (mv^2)/r I = mr^2 I = I(cm) + Mx^2 v = v(0) + at x = x(0) + v(0)t + .5at^2 v^2 = v(0)^2 + 2a(x-x(0)) And for rotational mechanics, the analogs are: torque = F theta = x omega = v alpha = a L = p I = m This does not cover every single equation, but it hits the most important ones and can centralize your equation focus while preparing for the midterm.

It looks like kicking field goals has a lot to do with physics! Its also ironic that you used a picture of the patriots and both them and the falcons lost. #letsgobuffalo

"potentially hypothetically theoretically" - definitely the best part. This is very creative of you CharlieEckert, and I have to disagree with you goalkeeper0: in the real world, cheaters very often win.

Cross products are definitely strange, and I liked learning about angular momentum and rolling objects as well, though I'm not so crazy about how much more complicated energy problems are now than they were last year. And I'm a big fan of independent units as well.

Cool! So next time I need to really secure a lug nut, I should just use a 4 foot wrench. That would get the job done!

I agree! That would be a pretty awesome sight to see the ball drop right before midnight and then have the confetti explode exactly at midnight.

That's some crazy stuff. I wouldn't mind having that coating on my phone so it wouldn't get water damaged.

Its always a good sign when you say you're not quite sure in a post, but you were correct with the difference between the static and the kinetic friction. It is incredible how strong these men are. They probably worked at a auto shop or a farm or someplace where they just moved a lot of heavy stuff all day.

It is nice how now, with a stronger understanding of calculus, difficult physics integrals make much more sense now. And dont worry SwagDragon15, at least you understand now.

Interesting... Why is the frequency for larger animals so much smaller?

During a difficult test, its not to easy to increase h except maybe stopping and settling your brain down, but prior to a test you can study equations and concepts in order to increase h

In the famous Bible story of feeding the 5000, Jesus and his 12 disciples feed 5000 men with 5 loaves of bread and 2 fish. But, the 5000 only counts the men, and since these people have been following Jesus for over 2 days, it can be assumed that they are with their families. On average, we'll say that each man has a wife and two kids, speaking that some of the men weren't married and some of the men had much larger families. That means that this story is actually the feeding of the 20000. First, let's look at how much bread and fish would be needed to feed these people. According to Mark 6:42, the people "ate and were satisfied." These people hadn't eaten for 2 days as they've been following Jesus, so to eat and be satisfied, each person would need at least 2 fish and a loaf of bread. There needed to be 40000 fish and 20000 loaves of bread, meaning that Jesus multiplied the amount of fish by 20000 and the amount of bread by 4000, and that doesn't even include the extra 12 basket-fulls of bread that the disciples picked up afterwards. That's crazy! We can also see how long it would take to pass the bread around. The passage states that the people were divided into groups of 50 and 100, so if the groups are close to equal, there are 133 groups of 100 and 134 groups of 50 (267 groups in total). With large groups like that, the distance between the center of one group to the center of another was probably around 30 meters (close to 100 feet). The disciples had to pass around a lot of food to each group, so they likely stayed all together. Thus, they had to walk a 26700 meters to go to each group, and since the people ate and were satisfied, they probably wanted seconds, so that's actually 53400 meters with an average velocity of 1.4 m/s (the average walking speed). Using kinematics, we know that v = x/t, so t = x/v. Therefore, it would take 38143 seconds for the disciples to pass out that food, which is about 10 hours and 36 minutes. That's a lot of time! By understanding physics, you can appreciate the incredible awe of this miracle.