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Charles Hakes Fort Lewis College1. Charles Hakes Fort Lewis College2 Chapter 1 Newton and Gravity.

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Presentation on theme: "Charles Hakes Fort Lewis College1. Charles Hakes Fort Lewis College2 Chapter 1 Newton and Gravity."— Presentation transcript:

1 Charles Hakes Fort Lewis College1

2 Charles Hakes Fort Lewis College2 Chapter 1 Newton and Gravity

3 Charles Hakes Fort Lewis College3 Outline Notes Kepler Review Newton’s laws Gravity

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.

5 Charles Hakes Fort Lewis College5 Review Did not get thrown into the abyss: 1 Other favorite answers… The speed of light. I don’t know - I’m not king! My Holy hand grenade blew it up “42”: (mixing your fiction). I’m from Oklahoma and have no clue … for a chimney swallow while hunting mosquitoes….

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.

7 Charles Hakes Fort Lewis College7 Group Exercise Assume a comet has a period of 5.2 years, with eccentricity very close to 1.

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.

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.

10 Charles Hakes Fort Lewis College10 Figure 1.20 Isaac Newton ( )

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

12 Charles Hakes Fort Lewis College12 Newton’s “Laws”

13 Charles Hakes Fort Lewis College13 Newton’s 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.

14 Charles Hakes Fort Lewis College14 Newton’s 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.

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.

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

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 kg 1 m/day (~10 -5 m/s)

18 Charles Hakes Fort Lewis College18 Which object has the most momentum? A - A cruise missile B - A ship C - A glacier

19 Charles Hakes Fort Lewis College19 Angular momentum demonstration

20 Charles Hakes Fort Lewis College20 Angular momentum demonstration This is why planets move faster closer to the sun.

21 Charles Hakes Fort Lewis College21 Newton’s 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).

22 Charles Hakes Fort Lewis College22 Newton’s 2 nd Law Force - something that is capable of changing an object’s state of motion (it’s velocity) F net - the sum of all forces on an object Dynamics - the study of changes in motion and what causes those changes

23 Charles Hakes Fort Lewis College23 Newton’s 2 nd Law F net = m a

24 Charles Hakes Fort Lewis College24 Newton’s 3 rd Law …the one hard to believe…

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

26 Charles Hakes Fort Lewis College26 Newton’s 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.

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

28 Charles Hakes Fort Lewis College28 Gravity

29 Charles Hakes Fort Lewis College29 Figure 1.22 Gravity

30 Charles Hakes Fort Lewis College30 Figure 1.24 Sun ’ s Gravity

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

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

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

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 = 6.67x (N m 2 /kg 2 ) F = G M 1 M 2 / r 2

35 Charles Hakes Fort Lewis College35 Gravity F = G M 1 M 2 / r 2

36 Charles Hakes Fort Lewis College36 Newton Modification to Kepler’s 1 st Law Both the Sun and the planet orbit about the center of mass of the system.

37 Charles Hakes Fort Lewis College37 Figure 1.25 Orbits

38 Charles Hakes Fort Lewis College38 Newton Modification to Kepler’s 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 )

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.

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.

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.

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 today’s topics?


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