Palm Pipe Lab

This week in physics I missed the lab itself, but was able to get some serious work in with Ms. Tye after school.  I basically did a simulation of the lab again and was able to learn some awesome stuff regarding sound. Here's some terminology to learn before reading the rest of the blog:

• velocity: speed of sound; measured in meters per second (m/s)

• frequency: shakes per second; measured in Hertz (Hz)
• standing wave: stationary wave that remains in a constant with no net transport of energy
• harmonics: certain frequencies at which standing waves occur
• wavelength: length of wave; measured in meters (m)

An important equation:  velocity=(wavelength)(frequency)

BIG Questions:
How can we tell something (like sound) is a wave if it is invisible or too small for us to see?
How do musical instruments work?
What's the difference between a woodwind and a stringed instrument?



To make a musical note, participants had to hit one end of the pipe on our hands. This created a sound wave. But, since it is a closed end air column, there can only be odd-numbered harmonics. If there were even numbered harmonics, music wouldn't be possible. In woodwind instruments, the fundamental is 1/4 the wavelength whereas the fundamental on a stringed instrument will be 1/2 the wavelength.  The length of the pipe and its relationship with frequency is inversely related. The longer pipe will create a longer wavelength, decreasing the frequency of the wave. The shorter pipe creates a shorter wavelength, increasing the frequency of the wave.  Unfortunately I learned that music is actually math! Those are two things that I have different feelings for and to hear them associated together is "interesting" to say the least. The music that we hear in notes from instruments is really just proportional sound waves, and the note in which the amplitude is the highest determines what note we actually hear. Also an important factor when dealing with woodwind instruments is that the harmonics must be odd.  Here are example photos of each concept:

Magentism

Get ready to have your mind blown- EARTH IS IN FACT A LARGE MAGNET.  How is this possible you may ask?  The answer is inside.  At the very core of our planet are lots and lots of metals that are moving charges.  With that being said, Earth then becomes the perfect magnet.  Your next question is probably now, "why isn't everything magnetic or sometimes magnetic?" Well, that answer lies in the domain of the atoms.  The domain is when the atoms are magnetically aligned, and thus able to create attraction between charges.  So, a paper becomes a magnet only when in contact with a magnet because some of the atoms are aligned.  That's magnetism for you!

Circular Motion and Forces in 2D

Big Questions:
1. What does it mean to analyze forces in 2D?
2. How do forces cause object to move in a circle?
3. What does it mean to be in orbit? How do satellites orbit planets? How do planets orbit the sun?

For this weeks lab, we engaged in tasks that would give us insight on motion is 2 dimensions.  This is different from analyzing a force in 1D because you only measure one variable, x or y.  But, with 2D there is two!  This will incorporate geometry and our best friend SOH CAH TOA. 

With the hover disk lab we spun a hover disk, with a string attached to it, in a circle.  The hover disk is ACCELERATING.  How you ask?  Not because its speed is changing, but rather because its direction is changing.  In order for an object to accelerate a NET force needs to be acting on it.  When we let it go it traveled in a 90 degree angle.  Again, why?  Because of Newton’s 1^st law.  To address the third big question, the tension force keeps an object going in a circle (which is identified as orbiting).  This is how planets orbit the sun.  They are in a sense falling toward the earth.  Due to speed however they miss their target and keep on accelerating.  

Projectile Motion

This week for our lab the class furthered our knowledge of physics by studying projectile motion.  What is a projectile?  An object in motion with only the force of gravity that is influencing it.

 

How does one analyze projectiles?  For our class we went down to the gym and shot some hoops.  In the gym, we took videos of ourselves shooting (this is very accurate because one has to remember that a projectile will travel with a parabolic trajectory). 

 With the Vernier App we were able to plot our points in time (x and y coordinates seperately) and graph position over time with the velocity over time graphs.

With all of this information we were able to derive these equations

y=mx+b
y=acceleration
m=slop=velocity
x=time

Real Life application:

The best shooter of all time, Miami Heat guard Ray Allen, is an exceptionally talented athlete as well as physicist.  Allen understands the concept of projectile motion as he has made the most three pointers in NBA history and has a career free throw shooting percentage of 89.4%

Voltage

Lemon Lab:

Never in my wildest dreams did I think it was possible for a lemon to power a battery.  It turns out this is possible through voltage which is similar to that of a mountain.  Electrons go up and the protons go down the mountain creating charge!  This makes sense after taking the lemons and after sticking a penny and a nail inside the lemon we were able to see the scientifically beautiful results.  

The iPad is a staple in the education of an SI student nowadays.  This is possible through the lithium-ion polymer batteries that iPads use. These batteries have a long battery life because of their high power density. When charging the iPad battery, the voltage increases in the first two hours and stays constant for the final two hours. The iPad charges to 80% in very quick fashion which is why the voltage greatly increases for the first two hours. But when it reaches 80% the voltage is constant hence the large charging period.  The "mountain" is working a lot for the first two hours to charge the iPad and then works at a constant speed for the last two hours.  I have much more respect for the people at apple that develop this stuff!

http://www.apple.com/batteries/

Fan Cart Lab (Newton's Laws of Motion)

Big Question:
What is the relationship between Mass, Force, and Acceleration?

Introduction:
This week in physics we were able to learn about three very prevalent laws in our universe; Newton's laws of Motion!  To begin to understand this we needed to get some hands on experience, so Ms. Tye let us relax on a late Thursday afternoon and let us tackle some physics in the gym foyer!  We used some awesome hover cars that eliminated friction and combined this with some diagramming to help us realize why things happen the way they do.  Following that, in the second lab, we collided a fan cart with aluminum on the force probe.  After each of the five trials using a different mass, we used the wicked smart LoggerPro to calculate our slope which then equated acceleration. Once that was completed, we were able to derive the equation F=ma. 

Understanding this stuff
OK.  Now to really discern what this means we need to recap these three individual laws:

Newtons 1st Law of Motion: 
1. An object at rest or traveling at a constant speed will continue to do so, unless a net force acts on it.
2. An object moving at a constant speed or at rest has no net force acting on it.

Newtons 2nd Law of Motion:
-the amount that an object accelerates depends on the object's mass and the net force it experiences

Netwon's 3rd Law of Motion: 
Whenever two objects happen to interact, they each exert an equal but opposite force on the other.
The force that one object feels is the same type of force that the object feels, the same amount/magnitude of force that the other one feels, and the opposite direction of the force that the other object feels.
Example given in class: A mosquito crashes into a truck.  They exert equal but opposite force on each other.

Real World Connection:
A man that really understands Newton's Law of Motion is Cristiano Ronaldo.  Though I don't like him (he plays for Real Madrid and I like Barcelona, which is the biggest rivalry in soccer) I have to admit the man is a darn good physicist in his own right.  He understands how to strike the ball perfectly which prevents this amazing goal against Levante from becoming an NFL-esque field goal into the 15th row of the stands.  The strike of the ball itself incorporates the latter two of Newton's laws, while the dip into the back of the net is a perfect example of Newton's first law of Motion.  Enjoy!

Impulse Lab

Big Question:

What is the relationship between impulse, force, and time during a collision?

Intro:

In this week's lab we created a collision between an empty red cart into a force-probe with aluminum  attached to a ring stand with a heavier blue cart. We then deduced the velocity of the cart before and after the collision.  Finally came the determination of the impulse itself which by definition is a change in momentum. We did this to measure the relationship between impulse, force, and time during a collision since they are related to each other somehow.  Get ready to get your mind blown because there is some interesting stuff coming up!

Data:

Red Cart Velocity Before Collision:  -0.667 m/s
Red Cart Velocity After Collision: 0.609 m/s
Area of Force: -0.337 Impulse: J = -0.319

Comparing the area of the force vs time graph has showed us that it is roughly the same as impulse.  These two are equal and from there we were able to derive the equation J(impulse)= Force X time.

Big Ideas:

-Force and time are inversely related.  When force goes up time goes down and when time goes up force goes down.  

-In a collision the force is equal from both sides.  How can this be? Well in every situation where there is a collision the force exerted on an object is the same.  However what causes the great change in momentum is then the mass of the object, as the smaller object would have a much greater change in momentum and impact the overall impulse.

Real World Connection:

In soccer you must control the ball to win.  There are many times when the ball goes in the air and you must bring it down close to you.  How does one do this?  By applying the same physics laws as to that of airbags it is quite easy.  Stick your foot out until it makes contact with the ball and then remove your leg.  This will increase the time it takes to hit the ground, thus reducing the force.  Of course this is easier said than done, so I'll let FC Barcelona player Thiago demonstrate from this video I showed Ms. Tye in class last week.