Palm Pipe Lab

             

                                                   

       ~ This week we performed the palm pipe lab that allowed us to analyze closed end air columns.

- To produce a musical note, we, the students, had to hit one end of the pipe on our hands. This allowed a sound wave to occur. However, since it is a closed end air column, there can only be odd-numbered harmonics. If there were even numbered harmonics, there would be an anti-node at the open ended part of the pipe. 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 determines the type of note that we hear. I observed that the longer the pipe, the lower the note and vice versa. A longer pipe will create a longer wavelength, decreasing the frequency of the wave. The shorter pipe will create a shorter wavelength, increasing the frequency of the wave. 

~Using a fork, we attempted to try and calculate the frequency of our fork when we hit it to create a note. After hitting it, we placed it next to the microphone for data. Our labquest produced a chart that had many frequencies playing at the same time. However, one frequency had the highest amplitude. Since it had the highest, it would be the one that was heard. 

       

                                       

Light and Optics-Ansay

~My dog and a flat mirror: 

                                               

     ~In this picture, my dog is lying on my bed facing me and behind her is a flat mirror (door of my closet). In the mirror, you can see my dog's backside which is the side that is facing the mirror. But is that a real image? Is she really behind that mirror? Or is it just a virtual image that our mind puts together?

                                    

     ~ Light rays from her head that go straight towards the mirror will reflect back as it is perpendicular to the mirror. That ray itself would be where the normal line would go. Another ray that I drew from her head hit the straight mirror at an angle. I had to draw a normal line to determine the angle of incidence. I calculated a 25° angle. This means that the angle of reflection is 25°. Looking at the two rays of reflection from the head of my dog, they will never intersect at any point. This makes it a virtual image because it does not connect at any point in front of the mirror. 

     ~ So I traced back the angles of reflection all the way behind the mirror. And of course, they intersected at a point virtually. This virtual image connected at the same height as the object and the same distance away from the mirror. This is why my dog's reflection looks like she is the same distance away from the mirror. 

     ~ To determine the size of the reflected, virtual image, I drew a ray from one of her paws straight towards the straight mirror. It also reflects back at the same line because it is perpendicular to the mirror. I drew another incidence ray at an angle and drew a normal line to determine the angle of incidence. It was also 25° which means the angle of reflection would be 25°. These two rays of reflection also would never intersect at a real point. So our mind tricks us into seeing a virtual image where the intersect at a point behind the mirror. After drawing the reflected image, I determined that it was VIRTUAL, the SAME SIZE, the SAME DISTANCE, and UPRIGHT. 

     

Magnetism

~6.3: Explain how objects like the earth and metals can be permanent or temporary magnets.

       ~Earth: 

 

         -Inside the earth, there is the outer core and the inner core. The inner core is a solid that is continuously spinning. The outer core is molten rock that flows. The core has moving charges that in turn generate magnetic fields around the earth. The field lines flow from the north magnetic to south magnetic pole. 

(All of the moving charges inside the core of the earth generate the magnetic field lines around the earth). 

-the magnetic field lines from from the north magnetic to south magnetic (south geographic pole to north geographic pole)

~Domain: group of atoms that are magnetically aligned 

     The reason why magnets are permanently magnetic is because they have domains that are lined up. Some metal objects such as the paper clip are sometimes magnetic when in contact with a magnet. The domains of a paper clip will line up when in contact with the magnetic field of a magnet. The domains will become better aligned. Non-Magnetic Material such as paper will not be magnetic because its domain are never lined up even though it has magnetic fields. 

Voltage and the iPad

    ~This week we talked about voltage, electricity, and charge. Atoms are generally neutral meaning there is a balance of protons and electrons. Only electrons move from atom to atom. Protons stay put. More electrons means the atom is negative. Less electrons means it is positive. 

     To transfer charge, there is friction. Like charges will repel and opposites attract.
          Protons will be more attracted to electrons, and will do its best to repel other protons.

     ~Voltage is a field (force at a distance) that surrounds charged objects. It is the "mountain" and "space" between two object that allows for the flow of electricity. "Voltage is to electricity as height is to gravitational potential energy.

          Electric potential=Voltage

          Electric Potential Energy = (charge)(voltage)

The higher the voltage and more charge means greater U sub e. 

Real World Connection: 

     Apple chose to use the lithium-ion battery to run their devices. They use lithium because it has a high power density that gives a longer battery life. Every time a battery goes through a full charge cycle, it slightly has a smaller capacity. This is maybe because there are less and less chemical reactors. You are able to charge the lithium battery a large amount of times but it is finite. The iPad charger is 5.1 Volts meaning it has an electric potential capacity of 5 V.

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

Projectile Motion

     ~In this lab, we headed to the gym to analyze a launched projectile. A projectile is when an object is only acted on by the force of gravity. Using a basketball, one person threw the basketball in the air, while the other video taped. The force of gravity acted on the launched basketball and made it fall down. After, we analyzed the video and looked at the graphs made after making marks of the ball in the video. After making the blue marks, we opened the and looked at the x and y graphs. We looked for any slopes to see if there was acceleration.

X graphs: On the top graph, we see that the slope is constant and unchanging. It is not messy.

However, on the bottom graph, the line is straight but looks very crooked and messy because the scale of the graph is very small.

     -Because the bottom graph has no slope and is relatively constant, there is no net force.

                                                


Y graphs: The top graph looks like a parabola and has an acceleration because the slope is always changing.

On the bottom graph, the line is moving downwards and has a negative slope. The line also goes below the x axis because when the ball is in its highest point, it stops moving. At this moment, it starts to fall down. Because there are slopes, there is acceleration.

 

When we combined the slopes in our table we got an average of -10 m/s squared. In class, we found out that the slope is -g. 

The general path of motion is to go up and then down because of gravity. Gravity pulls the object down when it the object is launched forward or up. 

2D Force and Circular Motion

    To analyze force in 2D means that the single force acting on the object can be comprised of two parts or components. There is a force going upwards and a force going rightwards. The vertical component is the upward influence of the force, and the horizontal component is the rightward influence of the force (Forces in Two Dimensions). To measure the amount of a single vector, you must use the trigonometric functions. For an object to move in a circle, it needs a centripetal force to act on it. The net force must be towards the circle that acts as the centripetal force. Next, it needs acceleration. The object, when moving in a circle, is moving at a constant speed, but changes direction. At all instances, the object is moving tangent to the circle, but the net force makes it move in a circle. To be in orbit means to revolve around another object. Satellites orbit planets by having one force. The net force is the one directed towards the planet. The pull of gravity pulls the satellite in. While it is moving at a constant speed, it constantly changes direction, therefore it is accelerating. At all instances, the satellite is moving tangent to the circle. But the net force pulls it in making it move in a circle. Planets revolve around the sun in the same way. Planets have a net force directed towards the sun. The sun’s gravity pulls the planets in. At all instances, the planets too move tangent to the circle. But, the sun’s gravity pulls them in making them travel in a circle. 

Newton's 3 Laws of Motion

 ~ For the past two weeks, we have been studying Newton's three laws of motion by performing the hover disc lab and the fan cart lab.

Newton's 1st Law
     An object at rest or traveling at a constant speed will continue to do so unless a net force acts on it.
          -Any object moving at a constant speed or at rest has no net force acting on it.

     The hover disc lab allowed us to see how this law works.

With the hover disc turned on, at rest, and not pushed, it will not move because no net force has acted on it yet. Unless person 1 pushes it, it will remain at rest.

We can also see the forces that are acting on the objects. Person 1, 2 and the disc are being pulled down by gravity. But they are not falling through the ground because of the normal force that keeps them up. 

With the hover disc on, not being pushed, and moving toward person 2 at constant speed, it will continue to move until a net force is acted upon it. At this moment there is no net force acting upon it which means that it will continue to move. The only way that it will stop moving is when it is stopped by person 2. 

We can see the forces acting on person 1, 2 and the disc. They are being pulled down by gravity, but pulled up by their normal force.

Newton's 2nd Law

     Force = mass • acceleration

     The fan cart lab was a good example of this law.

With a .3 kg fan cart, and a constant force of .298, we measured the acceleration of the fan cart when turned on to high. Later on, we added weights to the fan cart to see how the acceleration would be affected. The sonic range finder allowed us to find the measurements on the computer. 

     Acceleration is ∆v (velocity) /∆t (time) = a (acceleration)

.3 kg cart: .6518 m/sec. squared

.5 kg cart: .4661 m/sec. squared

.6 kg cart: .4203 m/sec. squared

.8 kg cart: .2848 m/sec. squared

1 kg cart: .1568 m/sec. squared

1.3 kg cart: .1200 m/sec. squared

With this data, we can see that as mass goes up, acceleration goes down meaning they are inversely proportional. We also derived the equation F=ma.

Newton's 3rd Law

     When 2 objects interact, they exert equal and opposite force on each other. 

            -These forces are 1) equal in magnitude, 2) Opposite in direction, 3) The same type of force

From the hover disc lab, when the hover disc is moving and hits person 2's hand, the person's hand and the hover disc both will exert an equal force on each other, force normal.

 ~ Skydiving

Due to Newton's Laws of motion, this man will continue to move downward because there is a net force acting upon him. The force of gravity is pulling down and nothing is keeping him up because he is not touching the earth. He will have an acceleration because there is a constant force and he has mass. This is why this man will fall with acceleration.