HSC Physic Research Task
Assessment
Due Date: 3:30pm Tuesday, Week 9, Term 2 (26th of June 2018)
Assessment weighting: 20% (Marked out of 60 and then divided by 3.)
Length: 2500 to 3000 words, plus diagrams, pictures & bibliography. Please include a word count.
Task: Locate the necessary information sources and use them to answer the following questions.
Every question is marked out of 10.
1. Describe the contributions made by Robert Goddard to the development of space exploration.
Working:
Robert Hutchings Goddard was born on October 5, 1882 died on August 10, 1945. He was an American engineer, professor, physicist, inventor and father of modern rocketry alongside Konstantin Tsiolkovsky and Hermann Oberth. He was one of the first to be credited with creating and building the world's first liquid-fuelled rocket. Robert Goddard carried developing early liquid fuelled rockets with intention to carry out heavy payloads out of Earth atmosphere and reach magnificent altitudes. Over the course of his career, Goddard not only developed the theoretical calculations for rocket flight but also made practical advances in rocket design and construction. Goddard journey to becoming the forefront of space exploration and rocketry began in 1907. While being a student at Worcester Polytechnic Institute he experimented on how powerful a rocket powered gunpowder creating massive clouds of smokes in the Institute basement. By doing so he caused commotion and the gained attention from the Institute. He also discovered that the black powder used for pyrotechnics was not strong enough to propel a rocket, he began using liquid fuels. For 20 years he tinkered and experimented and repeatedly tested rockets, using various mathematics and necessary for rocket flights… During this time by 1912, he was the first to explore mathematically the practicality of using rocket propulsion to reach high altitudes and even the moon. Up until 1914, Goddard would secure two patents, one for a one for a multistage solid-fuel rocket and one for liquid-fueled rocket. This would mark the beginning of the western world’s rocketry development. Goddard used his own money to fund and provide works for his colleague about rocketry. He first bought some commercial rockets and measured their thrust using a ballistic pendulum, a heavy mass suspended by ropes, to which the rocket was attached. The rocket was fired, and the height to which the pendulum rose provided a measure of the total momentum imparted to it. (picture 1.a)
picture 1.a
By weighing the rocket before and after firing, Goddard could find the mass of the ejected gases and from that deduce velocity. For a 1-pound Coston ship rocket, he found that v was about 300 m/sec.
Furthermore, Goddard began by experimenting with gunpowder, and launched his first powder rocket at Clark University in 1915. He finds out that powdered rockets were inefficient, only 2 percent of the available energy was being converted into motion the rest was wasted as heat, light, sound, and incomplete combustion.
In 1888 Gustaf de Laval who had developed a nozzle for use in steam turbines to accelerate the steam and increase the efficiency of the turbine. The basic principle of this (picture 1.b)
picture 1.b
That subsonic gas will increase its velocity through a tube as it narrows, however, once this gas achieves supersonic speeds it begins to increase in speed as the tube widens. Goddard realized that the rocketry applications of this and applied it to his rockets to achieve a drastically higher 63% efficiency. The application of this nozzle to rocketry was essential to the feasibility of rockets and thus space exploration, and it is now used in almost all modern rockets. By 1915, Goddard was the first to prove by actual static that it would in fact be possible to propel a rocket through a vacuum, making space flight possible, as by Newton’s 3rd law, the force on the rocket would be equal and opposite to the force on the gaze.
In 1922, Robert Goddard used the idea of a liquid-fulled rocket proposed by Hermann Oberth and also by Tsiolkovsky. It would have two lines running into its combustion chamber, one feeding fuel, the other oxygen. Goddard designed the two lines to pumped gasoline and liquid oxygen at a steady rate, and one was to pump sup zero liquid oxygen that was extremely cold and dangerous. The high temperature of combustion in pure oxygen required heat-resistant materials. He would continue to improve, and found that by using the liquid oxygen to cool the combustion chamber as it passed from the fuel tank he relieved many of the heat related issues. The nozzle and the "bell" guiding the expanding jet are lined with a large number of metal pipes, through which the cold fuel flows on its way to the combustion chamber. This innovative design of his would also prove essential for later space flight and is still used in modern rockets. Picture 1.c
picture 1.c
On March 16, 1926, Goddard flight-tested his first liquid-fuel rocket. His rocket design worked, but did not produce the hoped-for stability. The rocket burned about 20 seconds before reaching sufficient thrust for taking off, due to significantly high temperature melted the nozzle of the rocket. The rocket only reached to a height of 12.5 meter, levelled off and later hit the ground, all within 2.5 second.
Due to Robert Goddard rocketry innovation and popularity, given birth to developments of many more rockets thrust in jet engine for commercial use and also military applications such as the V-2 missiles, including gyroscopic control, steering by means of vanes in the jet stream of the rocket motor, gimbal-steering, power-driven fuel pumps and other devices. In 1929 Robber Goddard become the first scientist to develop and rocket that carried the first scientific payload, a barometer, and a camera. Goddard developed and demonstrated the basic idea of the “bazooka” two days before the Armistice in 1918 at the Aberdeen Proving Ground in Maryland…
In the years following until his death from cancer in 1945, Goddard continued to
work to build better, faster, more efficient rockets. 1932: First to use vanes in the rocket motor blast for guidance, 1932: First to develop a gyro control apparatus for rocket flight ,1935: First to launch a liquid-propellant rocket that attained a speed greater than the speed of sound.
Bibliography:
https://www.nasa.gov/missions/research/f_goddard.html
https://www.space.com/19944-robert-goddard.html
https://earthobservatory.nasa.gov/Features/Goddard/goddard_4.php
http://www.phy6.org/stargaze/Sgoddard.htm
https://www.massmoments.org/moment-details/robert-goddard-launches-space-age.html
https://en.wikipedia.org/wiki/Robert_H._Goddard
https://www.nasa.gov/centers/goddard/about/history/dr_goddard.html
https://www.google.com/search?q=Gustaf+de+Laval+nozzle&safe=strict&client=safari&channel=mac_bm&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi48Ov6iPDbAhVFPrwKHfJkAbMQ_AUICigB&biw=1440&bih=839#imgrc=RzxfjWK9qNPT3M:
https://onlinelibrary.wiley.com/doi/pdf/10.1002/0471743984.vse3660
(974 words)
2. Explain the operation of the loudspeaker and the moving coil galvanometer, with special reference of the role of magnetic fields and the Motor Effect in these devices. Do not refer to attraction or repulsion in your answer.
The operation of Loud speakers and the moving coil galvanometer are the same based on a phenomenon called the motor effect. The motor effect (principle) is when an electric current flow through a conductor (wire) produce a magnetic field. When this conductor (wire) is then placed in another magnetic field, the two, magnetic field from the conductor (wire) and the external magnetic field interacts causing the conductor (wire) to move due to due to the magnetic force created. Picture 2.a
picture 2.a
A loudspeaker is an electroacoustic transducer which converts an electrical audio signal into a corresponding sound. The most widely used type of speaker in the 2010s is the dynamic speaker. The dynamic speaker operates on the same basic, to produce sound from an electrical signal. In a loudspeaker, it consists of a fabric, coil, paper, or lightweight metal cone (called a diaphragm) with the outer rim attached to the outer rim of the loudspeaker case. The inner part of the cone is then attached to a coil (the coil which is wrapped around a circuit with electrical signal), which is mounted inside the magnetic field of a permanent ring magnet with one pole on the inside and the other on the outside. Picture 2.b
Picture 2.b
A loudspeaker works by transferring electric energy into sound energy (applying an AC current across the coil). A loudspeaker usually has a circular magnet that one pole on the outside and the other on the inside. There is a coil of wire sits in the space between the poles creating a magnetic field. This coil is connected to an amplifier to which changes the direction of the sound which has the same frequency by providing a current and increase sound energy. The current also changes magnitude and amplitude of the sound. Since the current passes through the coil in the magnetic field it will experience a force called the motor effect (where the coil moves effecting the magnetic field of the 2 poles). Since this magnetic force is large, it is then can be applied to the diaphragm attached to the coil as well, causing it to displace the air around it and thus generate sound, which in this example would be a loud, high pitched sound. Picture 2c
A moving coil galvanometer operates similarly to the to a loudspeaker using the motor effect, but with a much smaller DC current by transferring electric energy into sound energy to measure direction and magnitude of a current in any circuit. A coil galvanometer is all connected in series, having a fixed iron core which is wrapped in wire and place between 2 poles of a permanent magnet (similar to the Loudspeaker characteristics). Picture 2d
picture 2d
As shown in picture 2d, the permanent magnet is curved. This curvature is so that the magnetic field will become a radial field (field in a circle). The coil is always parallel to the field in order for torque (magnetic force produced in radial field) to be constant.
The needle rotates when there is a current passing through the circuit experiencing a force, the needle will try and equalled by the counter balancing screw. The needle will try and matches a position on the pre-calibrated scale and indicates the direction and magnitude of the current through the circuit.
Bibliography:
https://www.google.com.au/search?q=moving+galvanometer&safe=strict&tbm=isch&source=iu&ictx=1&fir=mPxtZRXi7UQMPM%252Cwsbu1hSs8wLKvM%252C_&usg=__IJ_Mv9ADOSWc8FKvV_92Ucac_y8%3D&sa=X&ved=0ahUKEwjJn7PotPDbAhXEi5QKHXwjD88Q_h0I6wEwIA&biw=1440&bih=803#imgrc=mPxtZRXi7UQMPM:
http://www.bbc.co.uk/schools/gcsebitesize/science/triple_aqa/keeping_things_moving/the_motor_effect/revision/2/
http://www.theloudspeakerkit.com/loudspeaker-components/
https://en.wikipedia.org/wiki/Loudspeaker
https://www.google.com.au/search?q=motor+effect&safe=strict&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiO7djrnvDbAhXKv7wKHc2PANAQ_AUICigB&biw=1440&bih=803#imgrc=65UHX1hCpq8TJM:
http://www.bbc.co.uk/schools/gcsebitesize/science/triple_aqa/keeping_things_moving/the_motor_effect/revision/1/
https://en.wikibooks.org/wiki/GCSE_Science/The_motor_effect
http://hyperphysics.phy-astr.gsu.edu/hbase/Audio/imgaud/spk2.gif
https://www.toppr.com/guides/physics/moving-charges-and-magnetism/moving-coil-galvanometer/
https://hemantmore.org.in/foundation/science/physics/moving-coil-galvanometer/2896/
http://hyperphysics.phy-astr.gsu.edu/hbase/Audio/spk.html
http://www.hk-phy.org/articles/speaker/speaker_e.html
https://www.electronics-notes.com/images/loudspeaker-moving-coil-cross-section-01.png
https://www.explainthatstuff.com/loudspeakers.html
(568 words)
3. Explain how Electromagnetic Induction and eddy currents are utilised in induction cook-tops.
Electromagnetic Induction is a type of Induction cooking where it heats a up cooking material using magnetic induction (magnetic field), instead of heating cooking materials using thermal (flames), or an electrical heating element such as a stove… Due to inductive heating directly heats the cooking material, very rapid increases in temperature can be achieved. The induction cooktop utilises the principal of Lenz’s law where when there is a change in magnetic flux, the current will be induced and oppose the change in magnetic flux. This helps heat up pans and pods (except for copper and aluminium) which is ferromagnetic materials.
In an induction cooktop, a coil of copper wire is placed under the cooking pot and an alternating electric current is passed through it (high frequency AC current). The results of this is that produces a magnetic field around the coil induces a magnetic flux which repeatedly magnetises the pot, treating it like a magnetic core of a transformer. This produces large eddy currents in the pot, which because of the resistance of the pot, heats it.
PICTURE 3a
The material use for induction cook-top is also very important because most non- ferromagnetic metals require a lot of magnetic fields force to heat up also because it relies where when a current move through a high resistance conductor, a lot of energy is expended as heat, whereas normally this is an issue that for most circuits one tries to minimise. A low ferromagnetic metal with too low of a resistance will also take much longer to heat up. So usually a ferromagnetic metal with moderately high resistance will be used on the cooktop. For nearly all models of induction cooktops, a cooking material must be made of, or contain, a ferromagnetic metal such as cast iron or some stainless steels. Furthermore, having too small or large a pot are also issues for the cooking capabilities, with a minor risk of melting/softening for some particularly small pans.
Induction cooking is quite efficient, which means it puts less waste heat into the kitchen, can be quickly turned off, and has safety advantages compared to gas stoves. Cooktops are also usually easy to clean, because the cooktop itself does not get very hot.
Bibliography:
http://lrrpublic.cli.det.nsw.edu.au/lrrSecure/Sites/Web/physics_explorer/physics/lo/induction_09/induction_09_06.htm
https://www.google.com.au/search?q=induction+cooking&safe=strict&dcr=0&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiz7cS2vfDbAhUBw5QKHRviCIwQ_AUICigB&biw=1440&bih=803#imgrc=-fdWZBqZygt-AM:
https://en.wikipedia.org/wiki/Induction_cooking
https://dc.edu.au/wp-content/uploads/induction-cooktop1.png
https://van.physics.illinois.edu/qa/listing.php?id=10098
http://www.scienceofcooking.com/induction_cooking.htm
https://www.popularmechanics.com/home/how-to/a5966/how-induction-stoves-work-how-the-heat-happens/
https://www.explainthatstuff.com/induction-cooktops.html
(Word 379)
4. Describe and assess the value of Einstein’s contribution to Quantum Theory and its relation to black body radiation.
During one of Hertz experiments to measure the speed of waves, Albert Einstein discovered that the speed remained the same, which supported Maxwell’s theory. He also uncovered the photoelectric effect. He also developed these ideas based by fellow physicist Max Planck.
A black body is one that absorbs or emits all incoming radiation. The Ultraviolet Catastrophe occurred when classical physics failed to meet experimental results. This is when a black body absorbs all incoming radiation and is it gets hotter. Further, it will emit radiation with a wavelength dependant on the black body’s temperature. The classical Physic predicted the wave energy intensity increased infinitely, When the wave model of the energy is decreased, however this in itself would be a violation of the law of conservation of energy. The experimental results reflected how classical theory was incorrect, since the peak wavelength increased as temperature increased, but all shorter wavelengths after this decreased in intensity.
Due to this experiment lead to Planck and his hypothesis, that all energy emitted and absorbed by a black body is quantised and occurs in discrete amounts called quanta.
Einstein stepped in and proposed that all EMR is composed of these discrete packets of energy now called photons. He took this theory further, applying it to explain the photoelectric effect. with energy of E = hf. When a matter and photons interacts, they cancel out or transfer energy. Thus, Einstein’s light model offers a wave-particle duality of light, in which it has a dual nature, such as wave properties and particle properties where photons act like small particles.
Bibliography:
http://www.sparknotes.com/biography/einstein/section9/
https://link.springer.com/chapter/10.1007/978-3-662-02994-7_11
https://atarnotes.com/forum/index.php?topic=168416.0
http://www.hyperhistory.com/online_n2/History_n2/index_n2/einstein_theory.html
https://phys.org/news/2014-06-einstein-quantum-mechanics-hed-today.html
(Word: 269)
5. Summarise how the Photoelectric effect is used in vacuum tube photocells (phototubes).
The photoelectric effect is the emission/ejection of electrons from the metal surface as a result of incoming light, and is absorbed by the electrons (Specific wavelength of light). This is due to quanta of energy in light increase with decreasing wavelength and at a specific amount which differs for each metal. This energy then helps exceed what is necessary to give the electron the velocity necessary to escape the metal surface. The absorbed energy of the electron is given by the formula E=hf, where f is the frequency of the photon and h is Planck’s constant.
A vacuum tube photocell (photoelectric cell) utilises this by placing a photosensitive cathode in an electron tube (vacuum tube) and controlling the flow of electrons through photoelectric emission rather than thermionic emission. The energy of the photon is directly proportional to the frequency of the incident light, and the energy required to “liberate” an electron from the metal is dependent on the material itself and is called the threshold frequency of the material. Once an electron has been liberated, energy is dependent on the material of the cathode.