Daniel+K

Daniel Kahn 3/22/11 McCoppin Electronic Devices: Entry #1 Analog signals are different from digital signals because an analog signal is a signal that varies smoothly in time. In an analog electronic signal the electric current increases or decreases smoothly in time. However, digital signals don’t vary smoothly, they jump and skip. Semiconductors are useful in electronic devices because unlike regular conductors, they can be controlled by adding impurities. The process of adding impurities is called doping. Doping can produce two different kinds of semiconductors. A diode is a solid state component that allows current to flow in one direction. They are used when converting alternative currents. A transistor is used to amplify signals in an electric circuit. An integrated circuit contains large numbers of interconnected solid-state components and is made from a single chip of  semiconductor material.

It is crucial that we (NASA) have electronics if we plan to find life on Mars. Objects such as cameras are very important; however that isn’t the big picture. This is because if we want to get things to Mars, like rovers, programming and electronic devices are vital. To land on Mars, the rover must have electronic programing. And then, when we are there, the search for life begins with electronic devices. Life is just finding people or aliens. Anything like a plant can be life, so when one of the rover’s wheels broke, it dug into the ground and a white substance was spotted by scientist. It was some sort of chemical and it was said since the chemical was there, it is likely that water was there first. And water is a signal of life. The entire rover exploration was because of electronic devices. And then, we stumbled upon a sign of life without meaning to. Our world counts on electronic devices.

Good job on describing the questions and having full thorough answers. Kevin K

//Ms. Mc: Good overview of electronics and suggestions for how we would use electronic devices on our mission to Mars. A couple more specific examples (i.e., computers, communications systems, solar panels) is all I would add. 9.5/10//

4/5/2011 Entry #2 History of Rockets

Rockets have been around since 100 B.C.; however the first true rocket was used in 1232. At this time, the Chinese and the Mongols were at war with each other. During the battle of Kai-Keng, the Chinese repelled the Mongol invaders by a barrage of "arrows of flying fire." These fire-arrows were a simple form of a solid-propellant rocket. A tube, capped at one end, contained gunpowder. The other end was left open and the tube was attached to a long stick. When the powder was ignited, the rapid burning of the powder produced fire, smoke, and gas that escaped out the open end and produced a thrust. The stick acted as a simple guidance system that kept the rocket headed in one general direction as it flew through the air. It is not clear how effective these arrows of flying fire were as weapons of destruction, but their psychological effects on the Mongols must have been formidable. Following the battle of Kai-Keng, the Mongols produced rockets of their own and may have been responsible for the spread of rockets to Europe. All through the 13th to the 15th centuries there were reports of many rocket experiments. In England, a monk named Roger Bacon worked on improved forms of gunpowder that greatly increased the range of rockets. In France, Jean Froissart found that more accurate flights could be achieved by launching rockets through tubes. Froissart's idea was the forerunner of the modern bazooka. Joanes de Fontana of Italy designed a surface-running rocket-powered torpedo for setting enemy ships on fire. Nearly all uses of rockets up to this time were for warfare or fireworks.

Rocketry has evolved overtime and in the 1900, an American, Robert H. Goddard (1882-1945), conducted practical experiments in rocketry. He had become interested in a way of achieving higher altitudes than were possible for lighter-than-air balloons. Goddard's earliest experiments were with solid-propellant rockets. In 1915, he began to try various types of solid fuels and to measure the exhaust velocities of the burning gases. While working on solid-propellant rockets, Goddard became convinced that a rocket could be propelled better by liquid fuel. No one had ever built a successful liquid-propellant rocket before. It was a much more difficult task than building solid-propellant rockets. Fuel and oxygen tanks, turbines, and combustion chambers would be needed. In spite of the difficulties, Goddard achieved the first successful flight with a liquid-propellant rocket on March 16, 1926. Fueled by liquid oxygen and gasoline, the rocket flew for only two and a half seconds, climbed 12.5 meters, and landed 56 meters away in a cabbage patch. For his achievements, Goddard was given the name Father of Modern Rocketry. By today's standards, the flight was unimpressive, but like the first powered airplane flight by the Wright brothers in 1903, Goddard's gasoline rocket was the forerunner of a whole new era in rocket flight.

Nowadays, rockets are being used for military purposes.



Fig. 2 Hero Engine



Fig. 2 Chinese Fire Arrows //Ms. Mc: Excellent summary of the history of early rocketry and of modern rocketry right up to the end of your discussion. Althought some rockets are used for military purposes, most are used to deploy communication systems (i.e., satellites) and to explore space. Please insert your drawings/photos in your text where you discuss them. 14/15//

4/4/2011 Entry #3 Rocket Flight Stages Simulation

Click the green flag to start the simulation, and click the red stop sign to stop it. They are both located at the top right of your screen. Enjoy!

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4/13/2011 Entry #4 Rocket Parts

A rocket has several different components, all of which help the rocket in different ways. The nose cone on the top of the rocket, helps give the rocket some aerodynamics for less wind resistance. The body tube is the long tube which all of the components are attached, like the base of the rocket. The body tube is usually a strong cardboard/paper tube. The recovery system is the parachute inside the rocket that deploys at the apogee of the flight. The parachute allows the rocket to be used multiple times with minimal wear. Recovery wadding is like the protector of the recovery from the rocket, which might scorch or damage the recovery system. The launch lug is the part of the rocket that connects it to the launcher, and guides the rocket for a straighter trajectory. The motor mount is the place where the rocket is held in place inside the rocket. The fins are a very important part of the rocket, guiding the rocket after it leaves the launcher. Last of all, the rocket motor is the propulsion system of the rocket. The engine gives the rocket power and allows it to shoot up into the air.

//Ms. Mc: Good explantion of the functions of the vari////ous rocket parts and good labels. Please include a caption for all figures/graphs/tables (-1). 19/20//

4/19/11 Entry #5 Rocket Lab Experiment

**THE APOGEE HEIGHT DUE TO A ROCKET’S MASS** **Daniel Kahn** **Cary Academy**

**INTRODUCTION** The purpose of this experiment was to see if the mass of the rocket affected the apogee height. Besides mass, there were other forces that could have affected the rocket. The forces that could have affected the rocket’s apogee were gravity, air resistance, and thrust. Gravity is t he force that attracts an object toward the center of the earth, or toward any other physical body having mass. This means the rocket had to have enough thrust (another force) to go upward and it overcame gravity and air resistance (another force). Air resistance works with gravity to stop the rocket from staying in the air and force it to go back downward towards the center of the earth. Air resistance opposes the force that keeps the rocket in motion. The force that makes the rocket go upwards is the force of the launch pad while the rocket is waiting to lift off and then, thrust from the rocket. The launch pad is going up and is equal to the force of gravity because of Newton’s third law, “Every action has an equal and opposite reaction”. Thrust is the stronger force that makes the rocket fly upwards. During lift off, the thrust has to be greater than gravity and air resistance or else the rocket will not fly. During powered flight, it also has to be greater than gravity and air resistance. During coasting, the rocket has no thrust and is traveling because of the inertia gained during powered flight. Lastly, at apogee, there is no thrust, inertia or air resistance. There is no air resistance because the rocket should have stopped at the apogee. The remaining force is gravity, which makes the rocket go downwards. It was hypothesized that overall, including the forces, the rocket with the least amount of mass would fly the highest because it would take less amount of thrust to make the rocket fly upwards, and therefore cause the rocket to go higher and faster.

**ABSTRACT** In the experiment, the independent variable was the mass, while the dependent variable was the apogee height. The two have a cause and effect relationship. The higher or lower the mass is, the higher or lower the apogee height is. In the experiment, there was a large range of apogee heights. The lowest apogee height was 61 meters, yet the rocket mass was the lightest. The highest apogee height was 93 meters, and the mass was 44.5 grams.



Figure 1: Cause and Effect of the Rocket's Mass and Apogee Height For the data above, multiple averages were taken. There was no mode, yet there was a mean and a median. The mean of the apogee height was 80.14 meters, and the median was 83 meters. Though, 80.14 and 83 meters were averages, the data got as low as 61 meters and as high as 93 meters. This confirmed that the data varied largely, and that the mass affected the rocket’s apogee because just a few grams made a 32 meter difference. In addition to the averages for the apogee height, averages for the mass of each rocket were taken as well. Once again, there was no mode, but there was a mean and a median. The median was 44.5 grams, while the mean was 44.14 grams. The data may have varied for several reasons; however the most likely was that the people that measured the apogee of the rockets were different each time. Hence, the rocket’s apogee height could have varied because the person that was holding the gun altered. There was a no relationship in the data, for the results were scattered and mixed around. This is caused because the change in the independent and dependent variables were not related; one did not affect the other. There was clearly no flagrant upward or downward trend.

**CONCLUSION ** It was earlier hypothesized that including the forces, the rocket with the least amount of mass would fly the highest because it would take less amount of thrust to make the rocket fly upwards, and therefore cause the rocket to go higher and faster. The hypothesis previously made was not confirmed. Instead of going the highest, the lightest rocket went the lowest. The lowest apogee height was 61 meters, while the highest apogee height was 93 meters and the mass was of the highest flying rocket was 44.5 grams. The rockets that flew the best were the ones that had a mass of around 44 grams, but this experiment demonstrates that if a measurement is just a few grams off, it makes a huge difference.

Entry 6

4/25/11
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas dust, and an important but poorly understood component tentatively dubbed dark matter. There are two main types of galaxies; they are called spiral and elliptical galaxies. Spiral galaxies form from the collapse of a protogalactic cloud. Spira l galaxies consist of three components: a rotating disk, a bulge and a halo. When the protogalactic cloud collapses, the stars in the bulge and halo form first. These stars have ra ther random orbits around the galactic center. The remainder of the cloud forms a disk due to the conservation of angular momentum (the same effect as the spinning up of the dancer when she pulls her arms inside). The stars in the disk form later and thus the disk population of stars are younger than those in the bulge and the halo. Further, the stars in the disk rotate around the center of the galaxy in a collective, well defined way unlike the stars in the bulge and halo. Elliptical galaxies are thought to be formed as a result of a merger of two disk galaxies. When two spiral galaxies merge, then the orbits of all the stars are randomized. As a result, all the stars in an elliptical galaxy have random orbits and there is not much collective motion of   stars. Figure 1: A Spiral Galaxy

A quark is a fundamental particle which possesses both electric charge and 'strong' charge. They combine in groups of two or three to form composite objects (called mesons and baryons, respectively), held together by the strong force. Protons and neutrons are familiar examples of such composite objects -- both are made up of three quarks.

The quarks come in six different species (physicists call them 'flavors'), each of which have a unique mass. The quarks names are: up quark, charm quark, top quark, down quark, strange quark, and bottom quark. The two lightest, unimaginatively called 'up' and 'down' quarks, combine to form protons and neutrons. The heavier quarks aren't found in nature and have so far only been observed in particle accelerators.

Figure 2: The Different Quarks





//Ms. Mc: Good answers and pictures. You were to refer to your figures in your text but since you have 2 extra pictures, I won't take points off for that. Please be sure to have a title for you entries (-1/2). 9.5/10//

Entry 5/5/2011 Challenge Description

For challenge three on the Mindstorms Program, the objective was to test if the sound and light worked. The goal was to stop the robot from rolling off the end of the table. The steps were basic, but involved the robot to be accurate because if not it would have gone off the table.

Block 1: Was a wait block that has the sound sensor connected to Port 2. The sound sensor waits to hear a sound louder than 50. Once the sound sensor hears the sound over 50, the robot moves to block 2. (The robot starts moving when you say “go.”) Block 2: This block is a movement block that tells the robot to go forward at 75% power for unlimited amount of time. (The robot moves forward forever until it detects the edge of the table.) Block 3: Another wait block, however it is the light sensor that is connected to Port 3. When the light sensor recognizes a light over 21 it activates block 4. (Robot stops before going over the edge of the table (no more than 5cm from the edge of the table) Block 4: This block was a movement block, however it did not move. It ordered the robot to stops. Robot says “watch out”

Challenge complete!