KICKSTART PHYSICS SPACE 1. SPEED AND ESCAPE VELOCITY 2. PROJECTILE MOTION 3. ACCELERATION AND G-FORCES 4. C AND RELATIVITY 5.

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1 KICKSTART PHYSICS SPACE 1. SPEED AND ESCAPE VELOCITY 2. PROJECTILE MOTION 3. ACCELERATION AND G-FORCES 4. C AND RELATIVITY 5. EINSTEIN Kickstat would like to acknowledge and pay espect to the taditional ownes of the land the Gadigal people of the Eoa Nation. It is upon thei ancestal lands that the Univesity of Sydney is built. As we shae ou knowledge, teaching, leaning, and eseach pactices within this Univesity may we also pay espect to the knowledge embedded foeve within the Aboiginal Custodianship of County. Fo moe infomation head to

2 Get to Know the Inne Risk Analysis Conduct a isk analysis by filling out the following table. List 3 isks to do with this investigation in the 2 nd yea lab. Also, list 3 isks in an industy whee physics is used. What ae the consequences of those isks? Use the isk matix below to make you judgment. What pecautions would you take to stop those isks fom coming about? What steps would you take to mitigate those isks? Risk Consequence Pecaution/Mitigation Kickstat Electicity Radiation Equipment Wate LN2 Electocution (High) Radiation Sickness (High) Tipping and Injuy (Medium) Slipping and Injuy (Medium) Fostbite (High) Safety Switch Low Dose/Shielding Don t Touch No Food/Dink in Lab Pesonal Potective Equipment Physics Industy Industy Finance/Tech, Games, Sola Powe, Medical Physics, Radiology Reseach Univesity, Academia Public Sevice CSIRO, DSTO, NMI, Questacon, Govenment, Teaches See above, jobs might equie moe specific consideations See above, jobs will equie moe specific consideations What sot of caees do you think you could get if you studied this topic at the Univesity of Sydney? 1

3 Speed & Escape Velocity Thee ae a numbe of diffeent types of obits in obital systems. Model each of the following obits with the gavity tampoline, and identify what object might have that obit. Type of Obit How to Model the Obit Examples of Objects with the Obit Highly Eccentic Obit Hypebolic Obit Give the object a push, but not stong enough to dislodge it fom making a complete obit Give the object a stong push to pevent it fom continuing obit Halley s Comet Asteoid Obital Decay Stat the obit with a slight push so that it decays towads the cente Intenational Station, LEO Afte modeling Low Eath and Geostationay Obits on the gavity tampoline, compae the two by listing thei similaities and diffeences. Similaities Diffeences - Eath obits - Used fo communications Remote sensing - Sees diffeent pats of the Eath - Diffeent obital speeds - Diffeent puposes We can use enegy and foce to detemine the velocity of objects as they leave the planet and into obit. Escape Velocity The kinetic enegy of an object with mass m is given by: E! = 1 2 mv! The gavitational potential enegy of an object with mass m in the gavitational field of an object with mass M is given by: E! = GmM Deive a fomula fo the escape velocity: E!! + E!! = E!! + E!! since final kinetic and potential enegies ae mv! GmM = mv! = GmM v! = 2GM v =! 2GM 2

4 Obital Velocity The equation fo the foce acting on an object with mass m and velocity v in a cicula path of adius is given by: (the centipetal foce) F = mv! The equation fo the gavitational foce between two objects with masses m1 and m2 is given by: F = Gm!m!! Deive a fomula fo the obital velocity: Since gavitational and centipetal foce ae pointed in the same diection, they ae equal: mv! = GmM! v! = GM v =! GM What do these fomulae say about the concepts of escape and obital velocity? Fo eithe obital velocity o escape velocity, we do not need to conside the mass of the object we ae concened with; it is not a vaiable! Keple s Laws Keple s thee laws of planetay motion descibe the motion of obiting bodies. They ae: 1. The obit of evey planet is an ellipse with the Sun at one of the two foci. 2. A line joining a planet and the Sun sweeps out equal aeas duing equal intevals of time: 3. T! R! Use the gavity tampoline to help demonstate each of Keple s thee laws of planetay motion. How would you deive Keple s 3 d Law fom the obital velocity of an object in obit? velocity = distance time = 2π T Substituting into ou obital velocity equation, 2π T =! GM 4π!! T! = GM Simplication and eaangement gives us:! T! = GM - that is, Keple's Thid Law! 4π! 3

5 Pojectile Motion Monkey and the Hunte Pedict Obseve Explain Above: Students make pedictions Miss In pojectile motion, gavity is acting on both of the object s vetical velocities, but not on it s hoizontal motion. Below: Students make pedictions Miss In pojectile motion, gavity is acting on both of the object s vetical velocities, but not on it s hoizontal motion. At: Students make pedictions Hit In pojectile motion, gavity is acting on both of the object s vetical velocities, but not on it s hoizontal motion. This pocess of Pedict, Obseve, Explain, Apply was used by David Unaipon ( ), known as Austalia s Leonado Da Vinci. He was of the Ngaindjei people of South Austalia and was an Aboiginal invento and autho who made significant contibutions to science. David invented many devices, including a sheep sheae that is still in use today. He neve eceived any ecognition o monetay benefit fom any of his innovative inventions. 4

6 Acceleation & G-Foces Acceleation Descibe how you moved fo each of the gaphs that you matched: Position vs Time Velocity vs Time Acceleation vs Time Featues Staight lines coespond to constant velocity; thee can be positive and negative diections. Hoizontal lines coespond to constant acceleation. Positive and negative values fo acceleation ae obseved. Chaacteistics Move fowad and back. Move fowad and back. Move fowad and back. Whee would you expeience the highest and lowest g-foce? Highest = whee acceleation is geatest and acting against gavity, lowest = whee acceleation is geatest and acting with gavity. 5

7 C & Relativity The Michelson-Moley Intefeomete Obseve the intefeence patten as you change the path length fo one of the light beams by caefully adjusting the position of the moveable mio. What happens to the patten? Sketch the intefeence patten you see though the view piece: 6

8 A Slowe Speed of Light Relativity is a vey difficult thing to study. This is why we use models and visualisations. With the game A Slowe Speed of Light you can qualitatively descibe some effects of elativity. Howeve, with all models, thee ae limitations and inaccuacies. Sometimes, the use of a model can actually have a negative effect on the intended pupose of the model. In the following table, list some limitations and inaccuacies to this model: Advantages Limitations Can visualise effects of speed of light tavel Easy to undestand demo of effects Can get some quantitative and qualitative data Not the full stoy Much moe complicated than pesented Inaccuacies and misconceptions can aise fom the model 7

9 Einstein An hou sitting with a petty gil on a pak bench passes like a minute, but a minute sitting on a hot stove seems like an hou. - Albet Einstein Using the equation fo time dilation: t! = t 1 v! c! fill in the table fo the effect of time dilation in days and yeas with espect to the pecentage of the speed of light. Speed (% of c) Days Yeas What is the time dilation expeienced by astonauts on the Intenational Station fom the efeence fame of people on the suface of the Eath? The obital speed of the ISS is 7.66 kms -1. t! = 1! ! c! = 1.01 days = yeas 8

10 Inetial Fames of Refeence vs Non-Inetial Fames of Refeence Inetial Fame of Refeence: The fame of efeence whee the Newtownian concept of inetia holds. Non-Inetial Fame of Refeence: The fame of efeence whee the Newtownian concept of inetia does not hold. How can we distinguish between the two? The easiest way to illustate this diffeence is with otating efeence fames. Why is that? Use the gaph pape to illustate the diffeence between inetial and non-inetial efeence fames: Inetial Fame Non-Inetial Fame 9