Uneventful Weekend - Centripetal Force

Well, I have had a fairly uneventful weekend (too much homework!) so when I remembered I had to do a Physics journal, I was quite at a loss for what to write about. Thankfully, I ran the wash yesterday so I'm going to write about the centripetal force in my washing machine. Unfortunately, I wasn't thinking about taking a picture of the wash so I only have pictures of the empty washing machine.

Anyway, the washing machine utilizes centripetal force during the spin cycle to remove excess water from your clothes so that they aren't dripping wet when you take them out. To do this, the little holes all along the sides of the washer are opened and as the washer continues to spin, centripetal force drives the water out. The water is small enough to fit through the holes and are therefore thrown out tangent to the circle by a lack of a normal force. As a result, all that is left in the washer are your slightly damp clothes which could not possibly escape through the holes.

So, that was my pretty lame journal for this weekend and now I have to go finish all the other homework that has caused my very uneventful weekend. Hopefully next time I will have a more recent physics concept to write about.

Physics in Magic - Static Electricity

Today my sister came home and told us all about this "really cool" demonstration their teacher did in science class. She said that their teacher seemed to "make the paper fly up and stick to the ruler like magic."

As she was describing this, I realized that it was most likely static electricity that caused the piece of paper to stick to the plastic ruler. So, I decided to try it myself. Using a plastic comb and a small piece of paper, I charged the comb by rubbing it vigorously against my shirt. As a result, when I brought it near the neutral piece of paper, it attracted the paper in an attempt to neutralize itself.

Specifically, the charged comb had either an excess or a deficiency of electrons. Since all objects want to be balanced/neutral, the comb was attempting to either gain or lose electrons in order to balance itself. To do this, it attracted the neutral piece of paper to attempt to lessen its charge.

I thought it was funny that I thought of static electricity when my sister described her teacher's "magic trick."

Torques - Turn on the Light!

Once we learned about torques, I came home and realized that there are torques everywhere in all sorts of everyday tasks. Things as simple as opening a door or even turning on a light. I actually thought of physics first when I opened the door, but since we used that example in class I decided to use the second torque I thought of and that was turning on the light.

In my house, the light switches are the regular flip-switches and I realized that, as small as it is, a torque is what makes it turn. The rotation point is inside the wall behind the plate, the lever arm is the protruding switch, and the force is provided by the finger that is flipping the switch.

Another regular task that reminded me of torques is, interestingly, flushing the toilet. The handle is the lever arm and the rotation point is the part that connects to the toilet. Again, you provide the force.

In fact, all the mechanical levers I can think of involve torques to operate. Can a person's limbs and joints also involve torques? Like the knee or elbow? I think it's amazing how many instances I can think of where torques were applied.

Boom Blox - Physics in Wii

My sister recently bought a new game called Boom Blox for the Wii. What I found most interesting about this game is the amount of physics involved in playing it.
The main goal of the game seemed to be to knock down all the blue cubes (or gems) through various creative means using as few throws as possible.
In addition, the Wii remote even allows the game to calculate how successful to make your throw based on how much force you put into it. It is not just enough to do the throwing motion, you actually have to put some muscle behind it to get a "Strong Throw". Otherwise you'll get a "Weak Throw" and the heavy blocks won't move very much.

I took a picture of my sister playing Boom Blox:

Specifically, there was one game called Teeter-Totter which required you to knock a heavy block onto the balance beam to tilt it and make all the gems fall.

Here are the before (the initial setup) and after (with the blocks falling) shots.

Overall, I was intrigued at how a very simple game of physics could be so much fun to play and yet I was hooked the first time I tried it. Without even really thinking about it, I was applying my knowledge of physics concepts like weight, force, projectile motion, velocity, etc. to help me win the game.

Cirque Du Soleil - Trapeze

On Saturday, I went with my family to see the Cirque Du Soleil show Saltimbanco. It was definitely worth it. It was humorous, the acts were amazing, and (of course) it had tons of good physics! Unfortunately, the show doesn't allow for any photography so the picture I posted is scanned from the official program book they were selling.

This was only one of the many amazing stunts they performed. If you look closely, (click on the picture for the full sized image) you'll see that the second girl is being held up only by the first girl's flexed foot! I thought this was incredible, especially when you consider how much downward force/weight her foot is supporting. In addition, the first girl isn't sitting firmly on the trapeze but holding on with one hand and her leg!

Another amazing stunt was when one man climbed up a pole using only his hands. He climbed straight up with only his hands touching the pole while keeping his body pretty much parallel to the pole. It's unbelievable to think how much strength that must require.

Overall, I was very impressed by the show and I think most people would enjoy it. If you've never seen a Cirque Du Soleil show, you should definitely consider attending one in the future. It was a wonderful mix of stunts, humor, and story and I would most certainly go again if I could.

Course Reflections

So far, I have been pleasantly surprised at how much I actually enjoy this course. Normally, I don't like science. But this year I am actually finding Physics to be a very fun class. Of course, I am worried that the material will get harder later in the year. But I have no doubts that class will still be fun.

My goals for this class, especially after having such a hard time in Chemistry last year, are to enjoy the experience, understand the concepts, and earn at least a final A- grade. Although, right now, I'm feeling that as long as I'm enjoying myself, I shouldn't be stressing too much over my grade.

I feel that, so far, I have been fairly consistent in my effort and performance on labs, quizzes, and homeworks. I think I should work at being more consistent on tests but, overall, I am ok with what I have done so far.

As for my "state of mind" about this course, I have, as you can see, chosen a balloon as my image. This is because I feel that while I am hovering around the same place grade-wise, sometimes I am confused at the beginning and my head is "full" of air rather than information. However, by the middle of the section I usually have begun to understand. At the same time, I chose a balloon to represent how much fun I am having in this class.

Overall, I am having a great time in this class and I hope the rest of the year will be just as enjoyable.

Newton's Laws in Action

On Saturday, we were at my sister's gymnastics class and I noticed a beginner's class jumping over small, padded blocks. As the kids jumped one by one, I realized that this was Newton's laws in action.
In order for the kid to jump over the block, he had to be able to exert enough upward force to counter the downward pull of gravity. By doing this he would be changing his net force. Initially, before he jumped, the boy would have a net force of zero and he was at equilibrium. At this point, the free body diagram would have two equal forces, the downward force of weight and the upward normal force.
However, in the instant that he jumped, by pushing off from the ground, the boy had increased the upward force and therefore caused his body to rise off the ground. In this instant his net force is no longer zero because the greater upward force means the two forces no longer cancel out.