Blog 11: Xylophone Fun

Although we may not realize it, even as little kids, physics was something we played with on an everyday basis.  This toy xylophone, for example, is a perfect display of sound waves.  When we hit the longer bars of metal on the red end of the xylophone, we hear a lower noise and when we hit the shorter bars on the purple side of the xylophone, we hear higher pitched sounds.  We hear different pitched noises by hitting the different lengths of bars on the xylophone because the frequency of the waves from each bar is different.  The pitches for the longer bars are lower because they have a slower frequency than the shorter bars that have a higher frequency and, therefore, a higher pitch.  So even though as children we do not realize it, as we pounded on the colorful bars of the xylophone, or the lacquered keys of a piano, we can hear the different sounds coming from each instrument because of the different sound waves that are produced.

Blog 10!: Jello Box Generator

As soon as Mrs. Chen introduced electromagnetic induction in class I couldn't wait to write my blog.  I finally had a perfect idea for it!  Immediately I thought of my jello box generator that I built in elementary school.

  

For once it was a good thing that I kept one of my old science fair projects.  To make this "generator" I cut a square in a normal jello box so that you can see the magnet spinning inside.  A nail going through the box holds the magnet in place and connects into the hand crank which turns the magnet.  And wrapped around the whole box is a coil of wire.



When the magnet spins, the angle of the of the magnetic field with respect to the the coil is constantly changing, causing a voltage to be induced in the wire, therefore, causing an induced current.  The light flickers because as the magnet is flipped 180 degrees as it turns, the poles of the magnet reverse, making the current also flip back and forth, making the current of the circuit an alternating current.

Blog 9: UFO Ball

From third to fifth grade, every year I went to an annual "space camp" called Future Flight Hawaii.  Although a lot of my friends think it's funny that I went to a space camp, it was still one of the vest experiences of my life.  Every year I came home with fun and interesting toys that was related to the things we learned at camp.  One of the things I brought home was this UFO ball.  Like the chicken Mrs. Chen used in class, this ball only lights up when you touch both metal strips at the same time.  This is because to have a current, you need two things, 1) a voltage difference and 2) a connected path.  The battery provides that voltage difference and touching both of the metal strips, which are conductors, provides the connective path for the current to flow through you and then the ball.  That is why when you take of either one of your fingers, the ball will stop flashing and making noise.

Blog 8: Static

Since my brother was on playing COD on the TV downstairs for hours already, I decided to watch a DVD on my grandma's old TV that we had upstairs.  It is a lot smaller than the one currently being fried by the continuous Call of Duty tweaking but it would do for watching a short movie.  When I turned on the TV I noticed that the arms of my hair were attracted to the TV screen (I put my head near the TV so that you can see the attraction better).  I immediately thought of how a balloon, when rubbed across someones head will also make one's hair stand up due to static electricity.  Because I did not know the reason behind this attraction, I used Google to discover that the screen is bombarded with electrically charged particles.  It makes sense now that your arms hairs, which are neutral, are attracted to the charged screen because the screen is trying to go back to neutral by giving off its electrons to your arm hairs.

Blog 7: Mind Reliever?

So as I am sure everyone was aware of, this weekend was the weekend before finals.  What does that mean?  Well, for me that usually means trying to get as much information into my head again (and this time retain it for a while longer) before getting swept up with all the other things that happens during school.  Unfortunately, I can only go on to study for only so many hours at a time.  Eventually I have to give my head a rest in order to start shoving more things back into my head.  And what's the best way to mindlessly do something?  By looking at a fan!  Unfortunately for my brain, I saw that blades of the fan had torque which is the force times the radius, in this case the length of the blades.  The fan while spinning also had moment of inertia which is the mass x radius squared.  Also, when I turned on the fan, it had angular acceleration which is equal to the net torque over the moment of inertia.  So much for a mindless activity.

Blog 6: A Simple Compromise

My dad got particularly excited about this blog as I finally asked him for an idea.  He quickly thought of ideas that were, although easy to do, way too complicated for me to comprehend.  That still did not stop him from shooting down my more simple and "fun" idea.  My idea was to grab the small step ladder we have in the kitchen, put a stuffed animal or something on one of the blades, and steadily increase the speed of the fan.  But, with more concern for the ceiling fan than the entertainment factor of doing a physics blog, my dad came up with a satisfiable compromise.  In this set up, my dad screwed a paper plate on to one of his power drills.  I placed a nickle on the platem started the drill slowly then started to turn up the speed.  Soon after increasing the speed, the nickle flew off the plate.  I now know that because the nickel's centripetal force, in this case it's friction, was not strong enough to keep it in it's circular path, it flew away from the center of the rotation on a tangent.

Angled Ramp (turn before tunnel on Likelike Hwy)





Blog 5: "Put your momentum behind it!"

When learning how to kick a ball properly, my coach always told me, "Put your weight behind the ball."  What my coach meant was to not just swing at the ball from your knee while standing still, but to run at the ball to run through the ball and kick from your hips.  But what my coach meant was "put your MOMENTUM behind the ball."  Momentum, p, is equal to mass X velocity.  Weight, mass X gravity, is different.  In other words, it is easier to kick a ball harder if you have a starting velocity added to your mass.  In the picture, my sister has a slight forward motion (every little bit counts) before she passes the ball around the defender.  The greater your velocity, the greater your momentum, and since momentum is conserved, the ball you kick will also have the same momentum.  So, I guess that's why theres so much running in soccer...