Year 12 Physics. 9.2 Space

Transcription

1 Year 12 Physics 9.2 Space

2 Contextual Outline Scientists have drawn on advances in areas such as aeronautics, material science, robotics, electronics, medicine and energy production to develop viable spacecraft. Perhaps the most dangerous parts of any space mission are the launch, re- entry and landing. A huge force is required to propel the rocket a sufficient distance from the Earth so that it is able to either escape the Earth s gravitational pull or maintain an orbit. Following a successful mission, re- entry through the Earth s atmosphere provides further challenges to scientists if astronauts are to return to Earth safely. Rapid advances in technologies over the past fifty years have allowed the exploration of not only the Moon, but the Solar System and, to an increasing extent, the Universe. Space exploration is becoming more viable. Information from research undertaken in space programs has impacted on society through the development of devices such as personal computers, advanced medical equipment and communication satellites, and has enabled the accurate mapping of natural resources. Space research and exploration increases our understanding of the Earth s own environment, the Solar System and the Universe. This module increases students understanding of the history, nature and practice of physics and the implications of physics for society and the environment. Syllabus Dot- Points 1. The Earth has a gravitational field that exerts a force on objects both on it and around it Students learn to: define weight as the force on an object due to a gravitational field explain that a change in gravitational potential energy is related to work done define gravitational potential energy as the work done to move an object from a very large distance away to a point in a gravitational field E p = G m 1m 2 r Students: perform an investigation and gather information to determine a value for acceleration due to gravity using pendulum motion or computer- assisted technology and identify reason for possible variations from the value 9.8 ms - 2 gather secondary information to predict the value of acceleration due to gravity on other planets analyse information using the expression: F = mg to determine the weight force for a body on Earth and for the same body on other planets - 2 -

3 2. Many factors have to be taken into account to achieve a successful rocket launch, maintain a stable orbit and return to Earth Students learn to: describe the trajectory of an object undergoing projectile motion within the Earth s gravitational field in terms of horizontal and vertical components describe Galileo s analysis of projectile motion explain the concept of escape velocity in terms of the: gravitational constant mass and radius of the planet outline Newton s concept of escape velocity identify why the term g forces is used to explain the forces acting on an astronaut during launch discuss the effect of the Earth s orbital motion and its rotational motion on the launch of a rocket analyse the changing acceleration of a rocket during launch in terms of the: Law of Conservation of Momentum forces experienced by astronauts analyse the forces involved in uniform circular motion for a range of objects, including satellites orbiting the Earth compare qualitatively low Earth and geo- stationary orbits define the term orbital velocity and the quantitative and qualitative relationship between orbital velocity, the gravitational constant, mass of the central body, mass of the satellite and the radius of the orbit using Kepler s Law of Periods account for the orbital decay of satellites in low Earth orbit discuss issues associated with safe re- entry into the Earth s atmosphere and landing on the Earth s surface identify that there is an optimum angle for safe re- entry for a manned spacecraft into the Earth s atmosphere and the consequences of failing to achieve this angle Students: solve problems and analyse information to calculate the actual velocity of a projectile from its horizontal and vertical components using : v x 2 = u x 2 v = u + at v y 2 = u y 2 + 2a y Δy Δx = u x t Δy = u y t a y t 2 perform a first- hand investigation, gather information and analyse data to calculate initial and final velocity, maximum height reached, range and time of flight of a projectile for a range of situations by using simulations, data loggers and computer analysis identify data sources, gather, analyse and present information on the contribution of one of the following to the development of space exploration: Tsiolkovsky, Oberth, Goddard, Esnault- Pelterie, O Neill or von Braun solve problems and analyse information to calculate the centripetal force acting on a satellite undergoing uniform circular motion about the Earth using: F = mv 2 r solve problems and analyse information using: r 3 T 2 = GM 4π 2-3 -

4 3. The Solar System is held together by gravity Students learn to: describe a gravitational field in the region surrounding a massive object in terms of its effects on other masses in it define Newton s Law of Universal Gravitation: m m F = G d discuss the importance of Newton s Law of Universal Gravitation in understanding and calculating the motion of satellites identify that a slingshot effect can be provided by planets for space probes Students: present information and use available evidence to discuss the factors affecting the strength of the gravitational force solve problems and analyse information using: m m F = G d Current and emerging understanding about time and space has been dependent upon earlier models of the transmission of light Students learn to: outline the features of the aether model for the transmission of light describe and evaluate the Michelson- Morley attempt to measure the relative velocity of the Earth through the aether discuss the role of the Michelson- Morley experiments in making determinations about competing theories outline the nature of inertial frames of reference discuss the principle of relativity describe the significance of Einstein s assumption of the constancy of the speed of light identify that if c is constant then space and time become relative discuss the concept that length standards are defined in terms of time in contrast to the original metre standard explain qualitatively and quantitatively the consequence of special relativity in relation to: the relativity of simultaneity the equivalence between mass and energy length contraction time dilation mass dilation Students: gather and process information to interpret the results of the Michelson- Morley experiment perform an investigation to help distinguish between non- inertial and inertial frames of reference analyse and interpret some of Einstein s thought experiments involving mirrors and trains and discuss the relationship between thought and reality analyse information to discuss the relationship between theory and the evidence supporting it, using Einstein s predictions based on relativity that were made many years before evidence was available to support it solve problems and analyse information using: 2 E = mc l v = l 0 1 v 2 t v = m v = t 0 c 2 1 v 2 c 2 m 0 1 v 2 c 2-4 -

5 Students learn to: Students: discuss the implications of mass increase, time dilation and length contraction for space travel Concept Map The main concepts in this module are organised as shown in the concept map below

6 Scope and Sequence Week Number Content Key Concepts 1 Gravitational force Gravitational fields 9.2.A Gravity Weight 2 Gravitational potential energy B - Projectile Motion Galileo s analysis Vertical and horizontal motion 4 Types of orbit Orbital speed 9.2.C Orbits Uniform circular motion Term 4 5 Kepler s law 6 Escape velocity Forces during lift- off D Launches Velocity boost/safe re- entry/slingshot effect 8 Michelson- Morley experiment Fundamental postulates 9.2.E Special Relativity Relativity of simultaneity 9 Time and mass dilation, length contraction Textbook References Preliminary Course Bosi, Stephen. 2009, In2 Preliminary / Stephen Bosi... [et al.] Pearson Australia, Sydney. HSC Course Bosi, Stephen. 2009, In2 HSC / Stephen Bosi... [et al.] Pearson Australia, Sydney

7 Study Guide A Gravity 9.2.A Conceptual Outline Gravity is a natural phenomenon by which physical bodies attract each other with a force proportional to their mass. In everyday life, gravity is most familiar as the agent that gives weight to objects with mass and causes them to fall to the ground when dropped. Gravitation causes matter to coalesce and remain intact, thus accounting for the existence of the Earth, the Sun, and most of the large objects in the universe. Gravity is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth; for the formation of tides; for natural convection, by which fluid flow occurs under the influence of a density gradient and gravity; for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena observed on Earth. Gravity is one of the four fundamental forces in physics, along with electromagnetism, and the nuclear strong force and weak force. Modern physics describes gravitation using the general theory of relativity by Einstein, in which it is a consequence of the curvature of space- time governing the motion of inertial objects. The simpler Newton's law of universal gravitation provides an accurate approximation for most physical situations and is the focus of study in this section of work. In this unit you will learn about: Newton's law of universal gravitation and those factors that affect the strength of gravitational force The gravitational field, how it is defined and measured Weight as another way of describing gravitational force Gravitational potential energy and those factors that affect it - 7 -

8 9.2.A Assumed Knowledge Concept Preliminary Dot- Points Nature of forces Explain the need for a net external force to act in order to change the velocity of an object Solve problems and analyse information using: F = ma Weight as a force Define the terms mass and weight with reference to the effects of gravity Chapter 3.1 What is force, pp Chapters Newton s laws of motion, pp Chapter 3.2 Mass and weight, pp A Assumed Knowledge Concept Preliminary Dot- Points In2Physics@Preliminary Work and energy Identify that a moving object possesses kinetic energy and that work done on that object can increase that energy Define the law of conservation of energy Chapter 4.1 What is energy, pp Chapter 4.2 Energy transformation and motion, pp Chapter 4.3 Work, pp

9 9.2.A Syllabus Dot- Points Gravitational force Gravitational fields Define Newton s Law of Universal Gravitation F = G m!m! d! Discuss the importance of Newton s Law of Universal Gravitation in understanding and calculating the motion of satellites Present information and use available evidence to discuss the factor affecting the strength of the gravitational force Solve problems and analyse information using: F = G m!m! d! Describe a gravitational field in the region surrounding a massive object in terms of its effect on other masses in it Weight Define weight as the force an object due to a gravitational field Gather secondary information to predict the value of acceleration due to gravity on other planets Analyse information using the expression: F = mg To determine the weight force for a body on Earth and for the same body on other planets Perform an investigation and gather information to determine a value for acceleration due to gravity using pendulum motion or computer- assisted technology and identify reason for possible variations from the value 9.8 ms - 2 Gravitational potential energy Define gravitational potential energy as the work done to move an object from a very large distance away to a point in a gravitational field E! = G m!m! r Explain that change in gravitational potential energy is related to work done - 9 -

10 9.2.A Resources Websites Twig- World Video Quarkology physics/92- space/92a- gravity.html Chapter Reference 1.2 Gravity, pp Gravitational potential energy, pp Gravity world.com/films/glossary/gravity- 516/ Weight world.com/films/glossary/weight- 566/ Gravitational Field world.com/films/glossary/gravitati onal- field- 515/ 9.2.A Student Activities Completed Textbook Checkpoint 1.2, p.16 Textbook Checkpoint 1.3, p.19 Textbook Chapter 1 questions, pp.23-24, Qs 5-9 & Tutorial 9.2.A Gravity HSC Questions 9.2.A - Gravity Experiment 9.2.A.1 Measuring acceleration due to gravity Activity 9.2.A.1 Newton s law of universal gravitation Activity 9.2.A.2 Weight in other parts of the solar system Activity 9.2.A.3 Gravitational potential energy

11 9.2.A Gravity Notes

12 Study Guide B Projectile Motion 9.2.B Conceptual Outline Projectile motion is one of the traditional branches of classical mechanics. A projectile is any body that is given an initial velocity and then follows a path determined by the effect of gravitational acceleration. The path of the projectile (trajectory) is determined by its initial velocity (magnitude and direction) and the acceleration due to gravity. Kicked footballs, objects dropped from airplanes and bullets shot from a gun are all examples of projectiles. Projectile motion is usually analysed by considering the horizontal and vertical components separately. There is no acceleration in the horizontal dimension; however, gravitational acceleration acts in the vertical dimension. Projectile motion may only be used to solve mechanics problems if the acceleration is constant. In this unit you will learn about: Galileo's analysis of projectile motion How to describe the path and motion of a trajectory How to analyse and calculate aspects of the motion of a trajectory such as time of flight, velocity and range 9.2.B Assumed Knowledge Concept Preliminary Dot- Points In2Physics@Preliminary Equations of motion (SUVAT equations) No specific dot- point Chapter 1.3 SUVAT equations, pp.9-12 Vectors Solve problems using vector diagrams to determine resultant velocity, acceleration and force Chapter 2 Heads and tails: vectors, pp

13 9.2.B Syllabus Dot- Points Projectile motion Describe the trajectory of an object undergoing projectile motion within the Earth s gravitational field in terms of horizontal and vertical components Describe Galileo s analysis of projectile motion Solve problems and analyse information to calculate the actual velocity of a projectile from its horizontal and vertical components using : v x 2 = u x 2 v = u + at v y 2 = u y 2 + 2a y Δy Δx = u x t Δy = u y t a yt B Resources Websites In2Physics@HSC Twig- World Video Quarkology physics/92- space/92b- projectiles.html Chapter Reference 1.1 Projectile motion, pp B Student Activities Completed Textbook Checkpoint 1.1, p.10 Textbook Chapter 1 questions, pp.23-24, Qs 1-4, & Tutorial 9.2.B Projectiles HSC Questions 9.2.B - Projectiles Experiment 9.2.B.1 Projectile motion

14 9.2.B Projectiles Notes

15 Study Guide C Orbits 9.2.C Conceptual Outline In Physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the centre of a star system, such as the Solar System. While the orbits of planets are typically elliptical, we approximate them to circular orbits in this section of the course. Circular motion is rotation along a circle: a circular path or a circular orbit. It can be uniform, that is, with constant angular rate of rotation, or non- uniform, that is, with a changing rate of rotation. Satellites orbiting the Earth and planets orbiting the Sun are examples of circular motion whereby the gravitational force keeps the mass orbiting at a certain velocity and radius. In this unit you will learn about: Uniform circular motion and its relationship to orbits and gravitational force Orbital speed and those factors that affect it Orbital shapes (circular, elliptical and hyperbolic) Kepler's laws (first, second and third) Satellite orbits (LEO and geostationary) Orbital decay and associated energy transformations

16 9.2.C Assumed Knowledge Concept Preliminary Dot- Points Uniform circular motion Solve problems and analyse information involving F = mv2 r Chapter 2.3 Circular motion, pp C Syllabus Dot- Points Uniform circular motion Orbital velocity Analyse the forces involved in uniform circular motion for a range of objects, including satellites orbiting the Earth Solve problems and analyse information to calculate the centripetal force acting on a satellite undergoing uniform circular motion about the Earth using: F = mv 2 r Define the term orbital velocity and the quantitative and qualitative relationship between orbital velocity, the gravitational constant, mass of the central body, mass of the satellite and the radius of the orbit using Kepler s Law of Periods Kepler s law Define the term orbital velocity and the quantitative and qualitative relationship between orbital velocity, the gravitational constant, mass of the central body, mass of the satellite and the radius of the orbit using Kepler s Law of Periods Solve problems and analyse information using: r 3 T 2 = GM 4π 2 Types of orbits Compare qualitatively low Earth and geo- stationary orbits Account for the orbital decay of satellites in low Earth orbits

17 9.2.C Resources Websites Twig- World Video Quarkology physics/92- space/92c- orbits.html Chapter Reference 2.2 Orbits and gravity, pp Beyond Kepler s orbits, pp Centripetal Force world.com/films/centripetal- force- 1500/ What is an Orbit? world.com/films/what- is- an- orbit- 883/ Satellites world.com/films/glossary/satelli te- 380/ The Satellite Story world.com/films/the- satellite- story- 872/ 9.2.C Student Activities Completed Textbook Checkpoint 2.2, p.41 Textbook Checkpoint 2.3, p.44 Textbook Chapter 2 questions, pp.54-56, Qs 8-11, 13-14, & 26 Tutorial 9.2.C Orbits HSC Questions 9.2.C Orbits Activity 9.2.C.1 Uniform circular motion Activity 9.2.C.2 Orbital velocity Activity 9.2.C.3 Kepler s third law

18 9.2.C Orbits Notes

19 Study Guide D Launches 9.2.D Conceptual Outline A rocket or rocket vehicle is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction. Rocket engines push rockets forwards simply by throwing their exhaust backwards extremely fast. Rockets for military and recreational uses date back to at least 13th century China. Significant scientific, interplanetary and industrial use did not occur until the 20th century, when rocketry was the enabling technology of the Space Age, including setting foot on the moon. Rockets are used for fireworks, weaponry, ejection seats, launch vehicles for artificial satellites, human spaceflight and exploration of other planets. While comparatively inefficient for low speed use, they are very lightweight and powerful, capable of generating large accelerations and of attaining extremely high speeds with reasonable efficiency. In this unit you will learn about: The launch velocity needed to escape the gravitational field of a planet The changing forces and acceleration during a typical rocket launch Ways to increase a rockets velocity using the Earth's rotational and orbital motion Factors that must be considered to ensure the safety of astronauts re- entering the Earth's atmosphere How the motion of planets can be used to enhance the velocity of a deep space probe

20 9.2.D Assumed Knowledge Concept Preliminary Dot- Points Net force and acceleration Explain the need for a net external force to act in order to change the velocity of an object Solve problems using vector diagrams to determine resultant velocity, acceleration and force Solve problems and analyse information using: F = ma Chapter 3.1 What is force, pp Chapters Newton s laws of motion, pp D Assumed Knowledge Concept Preliminary Dot- Points In2Physics@Preliminary Momentum Define momentum as: p = mv Explain why momentum is conserved in collisions in terms of Newton s Third Law of motion Work and energy Identify that a moving object possesses kinetic energy and that work done on that object can increase that energy Define the law of conservation of energy Chapter 4.4 Momentum, pp Chapter 4.5 Impulse, pp Chapter 4.1 What is energy, pp Chapter 4.2 Energy transformation and motion, pp Chapter 4.3 Work, pp

21 9.2.D Syllabus Dot- Points Escape velocity Explain the concept of escape velocity in terms of the - gravitational constant - mass and radius of the planet Outline Newton s concept of escape velocity Forces during lift- off Identify why the term g force is used to explain the forces acting on an astronaut during launch Analyse the changing of acceleration of a rocket during launch in terms of - Law of Conservation of Momentum - Force experienced by an astronaut Velocity boost Discuss the effect of the Earth s orbital motion and its rotational motion on the launch of a rocket Slingshot effect Identify that a slingshot effect can be provided by planets for space probes Safe re- entry Discuss issues associated with safe re- entry into the Earth s atmosphere and landing on the Earth s surface Identify that there is an optimum angle for safe re- entry for a manned spacecraft into the Earth s atmosphere and the consequence of failing to achieve this angle Space and rocket pioneers Identify data sources, gather, analyse and present information on the contribution of one of the following to the development of space exploration: Tsiolkovsky, Oberth, Goddard, Esnault- Pelterie, O Neill or von Braun

22 9.2.D Resources Websites Twig- World Video Quarkology physics/92- space/92d- launches.html Chapter Reference 2.1 Launching spacecraft, pp Momentum bandits: the slingshot effect, pp I m back! Re- entry, pp Saturn V Rocket Fuel Cylinders world.com/films/fly- me- to- the- moon- 963/ G- Force world.com/films/factpack- g- force- 1509/ Fighter Pilots: G- Force world.com/films/fighter- pilots- g- force- 1513/ Launch Window world.com/films/glossary/launc h- window- 362/ Fly Me to the Moon world.com/films/fly- me- to- the- moon- 963/ 9.2.D Student Activities Completed Textbook Checkpoint 2.1, p.35 Textbook Chapter 1 questions, pp.23-24, Qs Textbook Chapter 2 questions, pp.54-56, Qs 1-7, 12, & 25 Tutorial 9.2.D Launches HSC Questions 9.2.D - Launches Activity 9.2.D.1 Escape velocity Activity 9.2.D.2 Development of space exploration

23 9.2.D Launches Notes

24 Study Guide E Special Relativity 9.2.E Conceptual Outline In 1905, Albert Einstein published (among other things) a paper called "On the Electrodynamics of Moving Bodies" in the journal Annalen der Physik. The paper presented the theory of special relativity, based on two postulates. The first said that the laws of physics apply (are the same) in all inertial frames of reference (those that are moving with constant velocity or stationary). The second postulate stated that the velocity of light in a vacuum was always measured to be 3 x 10 8 ms - 1 (a constant) and is not relative to the motion of the observer or emitter of the light. While the first postulate was did not really tell scientists anything they didn't already know, the second one shook the scientific community to its foundations because of the consequences for our understanding of time and space. In this unit you will learn about: The Michelson- Morley experiment The difference between inertial and non- inertial frames of reference The fundamental postulates of the theory of special relativity and the consequences for space and time 9.2.E Assumed Knowledge Concept Preliminary Dot- Points In2Physics@Preliminary Frames of reference Describe the motion of one body relative to another Chapter 1.2 Section Relative velocity, p.8 Equivalence of mass and energy Identify that Einstein described the equivalence of energy and mass Chapter 15.4 Energy for stars, pp

25 9.2.E Syllabus Dot- Points Michelson- Morley experiment Outline the features of the ether model for the transmission of light Describe and evaluate the Michelson- Morley attempt to measure the relative velocity of the Earth through the ether Discuss the role of the Michelson- Morley experiments in making determinations about competing theories Gather and process information to interpret the results of the Michelson- Morley experiment Fundamental postulates Outline the nature of inertial frames of reference Perform an investigation to help distinguish between non- inertial and inertial frames of reference Discuss the principle of relativity Analyse and interpret some of Einstein s thought experiments involving mirrors and trains and discuss the relationship between thought and reality Relativity of simultaneity Describe the significance of Einstein s assumption of the constancy of the speed of light Identify that if c is constant then space and time become relative Explain qualitatively and quantitatively the consequence of special relativity in relation to: - the relativity of simultaneity - the equivalence between mass and energy Mass dilation Explain qualitatively and quantitatively the consequence of special relativity in relation to: - mass dilation Length contraction Explain qualitatively and quantitatively the consequence of special relativity in relation to: - length contraction Time dilation Explain qualitatively and quantitatively the consequence of special relativity in relation to: - time dilation Relativity effects Discuss the concept that length standards are defined in terms of time in contrast to the original metre standard Discuss the implications of mass increase, time dilation and length contraction for space travel 9.2.E Resources Websites In2Physics@HSC Twig- World Video Quarkology physics/92- space/92e- relativity.html Chapter Reference Chapter 3 Seeing in a weird light: relativity, pp Time Travel world.com/films/time- travel- 1441/

26 9.2.E Student Activities Completed Textbook Checkpoint 3.1, p.60 Textbook Checkpoint 3.2, p.64 Textbook Checkpoint 3.3, p.68 Textbook Checkpoint 3.4, p.74 Textbook Chapter 3 questions, pp.77-78, Qs 1-23 Tutorial 9.2.D - Relativity HSC Questions 9.2. D - Relativity Experiment 9.2.D.1 Frames of reference Activity 9.2.D.1 Special relativity

27 9.2.E Relativity Notes