Tuning Fork and Palm Pipe Lab

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 & a stringed instrument?

     In this lab, the class examined sound waves using a tuning fork and palm pipes. We were presented with two different sizes of tuning forks. When instructed, we struck the fork onto a firm surface, such as the heel of a shoe, and measured the different sound waves it produced. 
     A microphone attached to a LabQuest device recorded the sound waves and analyzed the different frequencies (in Hz) into a bar graph. The "peak wave" or the longest bar on the graph can be noted as the fundamental frequency. The fundamental frequency is the frequency that humans can hear the best. Other peaks in evenly spaced increments can also be known as harmonics. 
   With the Wolfram Alpha app on the Ipad, the peak frequency was translated into a specific note for each different tuning fork.

In the second part of this lab, we analyzed palm pipes and their relationship to sound waves. We were given pipes of varying lengths in order to discover the specific notes each one would play. By measuring the length and diameter of the pipe (in cm), my class could use the equation: L=1/4(wavelength) -1/4(Diameter inside) in order to solve for the wavelength. 

Ex: Length=0.092 meters

     Diameter=0.015 meters

0.092m= 1/4(wavelength)-1/4(0.015m)

0.368=(wavelength)-0.00375

wavelength= 0.37175 m

After finding the wavelength, we had to solve for the frequency with this equation: (velocity = frequency x wavelength) note: the constant speed in air is 343m/s

343 m/s= frequency (0.37175)        *remember we got the wavelength from the previous equation

frequency= 922.66 Hz

After finding the frequency, we input this data into Wolfram Alpha once more. 

Ex: 922.66 Hz= B flat note

  Each pipe of a different length had a different frequency and would make a different note. With the instruction from our teacher and a sheet of music, we reproduced the cliche song, "Twinkle Twinkle Little Star."

   A video about tuning forks and their relationship to instruments.

Optics and Lenses: Rainbows

Rainbows are formed when light from the sun refracts off of raindrops at a certain angle. That's why rainbows are often seen when the sun comes out after rain or other precipitation recently occurred. Red light is created when the angle of refraction is 40 degrees and blue (or violet) light is created at 42 degrees. All other visible light is in between the 40 to 42 degree range (a miniscule difference). All of the visible colors of the rainbow include: red, orange, yellow, green, blue, indigo, and violet.


Rainbows can also be reproduced artificially. One example of this is pure white light being shown into a prism. Prisms refract light as it enters through one side at a certain angle, bending the light. This creates the spectrum of seven colors as well.


Pink Floyd used the image of a prism and the spectrum of colors to grace the cover of his famous album "Dark Side of the Moon."


This short clip shows how a white light is altered and split into different colors with a prism.

Magnetism

A magnetic domain is a region in which the magnetic fields of atoms are grouped together and aligned. 

Metals like iron, cobalt, and nickel are always magnetic, meaning their domains are lined up permanently.

Certain objects, like paper clips, are magnetic only when they come into contact with magnetic objects. They have domains but they are not lined up unless contacted by a magnetic object.

Non-magnetic materials such as wood have no domains and can never be magnetic.

The Earth is a moving magnet because materials (metals like lead, cobalt, nickel and copper)
in the inner and outer core are spinning and flowing. Because moving charges create magnetic fields, this movement in the Earth's core creates its natural magnetic field. 

iPad Battery

A battery is a container consisting of one or more cells carrying an electric charge and used as a source of power.

The standard rechargeable iPad battery is composed of lithium polymer. Engineers prefer this material because of its reliability, ruggedness, and lower cost of manufacturing. Other uses for lithium polymer include radio control equipment and electric vehicles. It is rated at 5.1 Volts and is capable of 9 to 10 hours of life depending on its usage.

This battery is an ion, more specifically an anion. (negative charge) It belongs in the lower part of the activation series. It will likely receive electrons from a more positive substance.

The innovators at Apple are constantly aiming to improve battery life and reduce its size and recharge time.

http://www.channelinsider.com/c/a/Tech-Analysis/Apple-iPad-Scores-High-Marks-for-Battery-Life-201796/

http://www.lunacommerce.com/679-ipad-battery.html



As the battery technology has improved, the voltage (from IG to 3G) has improved to 3.75 Volts to 5.1 Volts while being virtually the same size. This has increased the battery life by several hours.

In this scenario, the cord of the charger provides the charge, the outlet acts as the voltage source, and the iPad battery is the resistor because it transforms electric potential energy.



In class we discussed that voltage is the electric potential of an object, a field surrounding charged objects.

Lithium polymer battery

A Lithium-Ion Polymer Battery used to power a mobile phone
specific energy	130–200W·h/kg[citation needed]
energy density	300 W·h/L[citation needed]
specific power	up to 7.5kW/kg[citation needed]
Charge/discharge efficiency	99.8%[citation needed]
Energy/consumer-price	1.5-1.7US$/A·h[1] (2.2-2.5 W·h/US$)
Self-discharge rate	5%/month[citation needed]
Time durability	24–36 months
Cycle durability	>1000cycles[clarification needed]
Nominal cell voltage	3.7 V

Martin Reynolds, a Gartner analyst explains that,"the iPad's relatively large battery can dissipate heat better than smaller batteries. This allows Apple to use a processor that generates more heat and runs faster without causing battery overheating -- a problem when a smaller battery takes up a confined space." 

The articles describe that due to these advancements, iPads are steadily becoming more useful and replacing laptops at a faster rate.

The use of the iPad example has helped me understand how the amount of voltage relates to real-world objects.

Projectile Motion Reflection on Learning

Our class discussed and experimented with the concept of projectile motion. We articulated our understanding of the conceptual aspect of projectile motion by writing on a whiteboard.

Using the Video Physics App on our iPads we recorded and analyzed the path of a basketball shot into the air. The app created graphs based off of the ball's trajectory.

The graphs demonstrate that the basketball moves in two dimensions, horizontal (Vx) and vertical (Vy),  and that gravity is the only force acting upon the object. The basketball shares similar traits to that of a projective which is defined as an object that moves in 2D with only the force of gravity acting.

The graphs also indicate that the basketball, and projectiles in general, move at constant velocity as indicated by the constant slope of they graph in the upper right corner. When the averages of the slope were averaged out among the class, the result was a slope of 10.2. This number is consistent with the gravitational force of the earth which is generally 10 N/kg.

In this experiment, human error was a major factor because the measuring of the ball's trajectory was done manually.

Forces in 2D and Circular Motion

Big Questions: 

What is a projectile? What is the general path of motion? Why?

Why do things fall? What is the acceleration due to gravity? Do heavier objects fall faster than lighter objects?

A projectile is an object moving in two dimensions in which the only force acting on it is gravity. The path of motion moves back towards the Earth because of the influence of gravity. All objects will fall at the same rate if the air does not act to slow them down (less air resistance).

1. What does it mean to analyze forces in 2D?
2. How do forces cause objects to move in a circle?
3. What does it mean to be in orbit? How do satelittles orbit planets? How do planets orbit the sun?

-Analyzing forces in 2D means to understand the behavior of forces in 2 dimensions, using both x and y coordinates. 

-Centripetal force causes objects to move in a circle. It is a "center-pointing" force in which a net force act towards the center of the circle. Force and velocity are perpendicular and tangent. Ex: The moon's continual orbit of the Earth.

- In regards to orbit, when an object is moving in a circle, it is accelerating. Its speed is not changing, yet, its direction of motion is changing. It also needs to experience an unbalanced force. 

Newton's Three Laws

                                            Design:        
                                           

Through the fan cart lab and hover disc lab that we did in our physics groups, we demonstrated and analyzed Newton's three laws of motion. In the hover disc lab, a device with a small fan at the bottom was used. This device could gravitate a few inches above the ground, counteracting friction. We described the relationships and natural forces that occur among the device, Earth, and two people who provided an outside net force. Interaction and free body diagrams can be used to map out the forces at work within this system. During the fan cart lab, we measured the amount of force a fan cart would project onto a sensor. We increased the amount of mass on the cart for every new trial as the distance and fan pressure remained constant.

                             Reflection:

The fan cart lab and hover disc lab satisfies Newton's first law. (which states that an object moving at a constant speed will stay that way unless it experiences a net force) The fan, which eventually attained a constant speed could, theoretically, never stop or slow down unless it experiences a net force. The net force in this case was a person's hand or the electronic probe. The hover disc, when pushed, could maintain a constant speed because of its ability to gravitate above the ground and counteract friction.
                  Both labs also describe the Second Law. (a net force will accelerate an object) The fan attached to the cart provided a steady force by which the cart could move. When the fan pressure was increased or if someone applied their hand to the cart, it would experience acceleration. The harder the force that was applied on the hover disc, the faster it would propel forward and the faster it would accelerate if it had already been moving.
                  The fan cart and hover disc labs illustrate Newton's third and final law of motion (for every action, there is an equal and opposite reaction). When the cart was forced against the sensor, it nearly bounced back to the same position that it started at. Some energy was lost as heat on the track. When a person pushes the disc against a wall, the harder they push the disc, the greater the distance of the recoil.

       
          Real-World Connection:

In regards to Newton's Third Law, a person discharging a firearm is a prime example. Guns with greater firepower produce much greater recoil and apply an equal and opposite force back to the shooter. A shotgun produces much greater recoil than a pistol.





Fun Fact: Newton first published his work, which included his three laws of motion, in the book Philosophiae Naturalis Principia Mathematica on July 5, 1687.