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Charles Hakes Fort Lewis College1 Slide 2 Charles Hakes Fort Lewis College2 Chapter 1 Newton and Gravity Slide 3 Charles Hakes Fort Lewis College3 Outline Notes Kepler Review Newtons laws Gravity Slide 4 Charles Hakes Fort Lewis College4 (Lab) notes Remove folder debris Do Kepler small group lab this week. Due Friday at 6:30 P.M. In box outside room 671. Sunset 2 - you MUST have Sunset 1 completed and returned FIRST Due Friday in one week. Slide 5 Charles Hakes Fort Lewis College5 Review Did not get thrown into the abyss: 1 Other favorite answers The speed of light. I dont know - Im not king! My Holy hand grenade blew it up 42: (mixing your fiction). Im from Oklahoma and have no clue for a chimney swallow while hunting mosquitoes. Slide 6 Charles Hakes Fort Lewis College6 Review What was the most important thing you learned? A circle is actually a special kind of ellipse with only one focal point A square is to a rectangle as a circle is to an ellipse The semi-major axis is half of the major axis. If the semi-major axis of two bodies is the same, they take the same amount of time to orbit. Slide 7 Charles Hakes Fort Lewis College7 Group Exercise Assume a comet has a period of 5.2 years, with eccentricity very close to 1. Slide 8 Charles Hakes Fort Lewis College8 Group Exercise Assume a comet has a period of 5.2 years, with eccentricity very close to 1. Calculate the semi-major axis. Slide 9 Charles Hakes Fort Lewis College9 Group Exercise Assume a comet has a period of 5.2 years, with eccentricity very close to 1. Calculate the semi-major axis. p 2 = a 3 What is the major axis? What is the maximum distance this comet might ever get from the Sun? Include copy of work in your folder. Slide 10 Charles Hakes Fort Lewis College10 Figure 1.20 Isaac Newton (1642-1727) Slide 11 Charles Hakes Fort Lewis College11 An iron weight and a styrofoam ball are dropped from the same height at the same time. Which hits the ground first? A) The iron weight B) The styrofoam ball C) They hit at the same time Slide 12 Charles Hakes Fort Lewis College12 Newtons Laws Slide 13 Charles Hakes Fort Lewis College13 Newtons 1 st Law If there are no external forces on an object, then: If it is at rest, it will stay that way - forever. If it is moving, it will keep doing so at constant velocity, in a straight line - forever. Slide 14 Charles Hakes Fort Lewis College14 Newtons 1 st Law Inertia - the natural tendency of an object to stay at rest, or remain moving with a constant velocity. Mass is a quantitative measure of inertia. Slide 15 Charles Hakes Fort Lewis College15 Momentum Momentum - the product of mass and velocity. momentum = mass x velocity A concept related to Inertia Momentum (both linear and angular) must be conserved. Slide 16 Charles Hakes Fort Lewis College16 Which object has the most momentum? A) A cruise missile B) A ship C) A glacier D) Need more information Slide 17 Charles Hakes Fort Lewis College17 Which object has the most momentum? A - A cruise missile 1000 kg 100m/s B - A ship 10 million kg = 10 7 kg 10 m/s C - A glacier 10 12 kg 1 m/day (~10 -5 m/s) Slide 18 Charles Hakes Fort Lewis College18 Which object has the most momentum? A - A cruise missile B - A ship C - A glacier Slide 19 Charles Hakes Fort Lewis College19 Angular momentum demonstration Slide 20 Charles Hakes Fort Lewis College20 Angular momentum demonstration This is why planets move faster closer to the sun. Slide 21 Charles Hakes Fort Lewis College21 Newtons 2 nd Law The net force on an object is equal to the mass of the object times the acceleration of the object F net = m a The SI units of force are newtons (N). Slide 22 Charles Hakes Fort Lewis College22 Newtons 2 nd Law Force - something that is capable of changing an objects state of motion (its velocity) F net - the sum of all forces on an object Dynamics - the study of changes in motion and what causes those changes Slide 23 Charles Hakes Fort Lewis College23 Newtons 2 nd Law F net = m a Slide 24 Charles Hakes Fort Lewis College24 Newtons 3 rd Law the one hard to believe Slide 25 Charles Hakes Fort Lewis College25 A brick hits a glass window. The brick breaks the glass, so the magnitude of the force of the brick on the glass is A: is greater than the magnitude of the force of the glass on the brick B: is smaller than the magnitude of the force of the glass on the brick C: is equal to the magnitude of the force of the glass on the brick D: none of the preceding Slide 26 Charles Hakes Fort Lewis College26 Newtons 3 rd Law For every action (force) there is an equal and opposite reaction (force). Important note - the action-reaction force pairs do NOT act on the same object. Slide 27 Charles Hakes Fort Lewis College27 A brick hits a glass window. The brick breaks the glass, so the magnitude of the force of the brick on the glass is A: is greater than the magnitude of the force of the glass on the brick B: is smaller than the magnitude of the force of the glass on the brick C: is equal to the magnitude of the force of the glass on the brick D: none of the preceding Slide 28 Charles Hakes Fort Lewis College28 Gravity Slide 29 Charles Hakes Fort Lewis College29 Figure 1.22 Gravity Slide 30 Charles Hakes Fort Lewis College30 Figure 1.24 Sun s Gravity Slide 31 Charles Hakes Fort Lewis College31 Gravity Any object having Mass will exert a gravitational force on other massive objects. Force is proportional to mass of each object F M 1 M 2 Slide 32 Charles Hakes Fort Lewis College32 Gravity Any object having Mass will exert a gravitational force on other massive objects. Force is proportional to mass of each object Force decreases with the square of the distance between the two objects F M 1 M 2 / r 2 Slide 33 Charles Hakes Fort Lewis College33 Figure 1.23 Gravitational Force Any object having Mass will exert a gravitational force on other massive objects. F M 1 M 2 / r 2 Slide 34 Charles Hakes Fort Lewis College34 Gravity Any object having Mass will exert a gravitational force on other massive objects. Force is proportional to mass of each object Force decreases with the square of the distance between the two objects Proportionality constant is G, the universal gravitational constant G = 6.67x10 -11 (N m 2 /kg 2 ) F = G M 1 M 2 / r 2 Slide 35 Charles Hakes Fort Lewis College35 Gravity F = G M 1 M 2 / r 2 Slide 36 Charles Hakes Fort Lewis College36 Newton Modification to Keplers 1 st Law Both the Sun and the planet orbit about the center of mass of the system. Slide 37 Charles Hakes Fort Lewis College37 Figure 1.25 Orbits Slide 38 Charles Hakes Fort Lewis College38 Newton Modification to Keplers 3 rd Law That math law - updated P 2 (years) = a 3 (astronomical units) M total (solar units) For planets around the Sun, this makes very little difference except for (even for) Jupiter (0.1% M sun ) Slide 39 Charles Hakes Fort Lewis College39 Which mass pair has the greatest gravitational force between them? 1: A 5M solar mass and a 4M solar mass separated by 4 AU. 2: A 4M solar mass and a 3M solar mass separated by 3 AU. 3: A 3M solar mass and a 2M solar mass separated by 2 AU. 4: A 2M solar mass and a 1M solar mass separated by 1 AU. Slide 40 Charles Hakes Fort Lewis College40 Which mass pair has the greatest gravitational force between them? 1: A 5M solar mass and a 4M solar mass separated by 4 AU. 2: A 4M solar mass and a 3M solar mass separated by 3 AU. 3: A 3M solar mass and a 2M solar mass separated by 2 AU. 4: A 2M solar mass and a 1M solar mass separated by 1 AU. Slide 41 Charles Hakes Fort Lewis College41 Group Exercise Calculate the force between those two masses. A 2M solar mass and a 1M solar mass separated by 1 AU. Slide 42 Charles Hakes Fort Lewis College42 Three Minute Paper Write 1-3 sentences. What was the most important thing you learned today? What questions do you still have about todays topics?