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Gravity. It’s the law. Obey it.

Gravity. It’s the law. Obey it. Or… Don’t let Gravity get you down. For the next clip, write down what you think is going through the person’s mind at the time. School appropriateness is crucial.

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Gravity. It’s the law. Obey it.

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  1. Gravity. It’s the law. Obey it. Or… Don’t let Gravity get you down

  2. For the next clip, write down what you think is going through the person’s mind at the time. School appropriateness is crucial. • Also write down what you think might happen if gravity worked in a different way or if we were on a different planet. In your notes…

  3. BEFORE

  4. What is going through his mind and what might this look like on a different planet or if gravity worked differently? • Remember… School appropriate 

  5. Songs by John Mayer, Sara Bareilles, Pixie Lott, Coldplay, A Perfect Circle • 9.8 m/s2 • Holds stuff down • A force that attracts objects together • Increases as the mass of the two objects increases • Decreases as the distance between the two objects increases What is gravity?

  6. Newton discovered gravity • Its always the same • If you drop two objects from different places, they fall in parallel paths to the ground • The pull of planets and stars will affect the outcome of a persons life based on their position in the sky at the time of the individual’s birth Misconceptions about gravity

  7. When we drop things they fall down • The Earth orbits around the Sun • The Sun moves around the Milky Way • Objects follow a trajectory when launched at an angle • Your atoms stick together Evidence for gravity

  8. Newton’s Law of Universal Gravity • The nearer or more massive 2 objects are, the greater the force of gravity between them • F=G*((m1*m2)/d2) • F is the force of attraction • m1 and m2 are the masses of the objects • d is the distance between the objects • G is the gravitational constant The Law of Gravity

  9. Not discovered by Sir Isaac Newton • Found by measuring the force in Newtons between two masses of 1 kg each, 1 meter apart • 0.00000000006667 N*m2/kg2 Or 6.667 x 10 -11 N*m2/kg2 • This is a very weak force • The crazy units make the end result come out in Newtons • How do you think this machine works? The Universal Gravitational Constant

  10. Cavendish Torsion Bar Gravity Balance

  11. Scientific Notation

  12. Used to make exceptionally large or exceptionally small numbers more manageable Scientific Notation

  13. If your starting number is large, you will have a positive exponent • If your starting number is small, you will have a negative exponent Scientific Notation

  14. Move the decimal point so that it causes the number to be greater than 1 and less than 10. • Example: 5,200,000. Converting from regular to scientific

  15. Next, count the number of times you moved the decimal point. This number will become an exponent. • 5,200,000 = 5.2 x 106 Converting from regular to scientific

  16. 0.0000314 Example: 3.14 x 10-5

  17. The exponent indicates which direction the decimal moves • 6.22 x 109 • 6,220,000,000 • 7.011 x 10-6 • 0.000007011 Converting from scientific to regular

  18. Linear speed - what we’ve already covered. Speed in a line • Rotational speed - Number of revolutions per minute • Tangential Speed – Speed of something moving along a circular path Rotational Stuff

  19. Centripetal Force – the force that causes an object to travel in a circular path • Centrifugal Force – a force that moves directly away from the center of a circular path Rotational Stuff

  20. Lets demo!!! • Artificial Gravity – Can we make it? • How? • Are you really feeling gravity? • What force are you feeling? Rotational Stuff

  21. When a quantity varies as the inverse square of its distance from its source. • Ex: the book uses an example of a “butter gun” Inverse Square Law Butter spray travels outward from the nozzle of the gun. Like gravity, the “strength of the spray obeys an inverse square law.

  22. Questions What does the very small value of the gravitational constant, G, tell us about the strength of gravitational forces? What are the 2 masses and one distance that determine your weight? Calculate the force of gravity on a 1-kg mass at Earth’s surface. The mass of Earth is 6x1024kg, and its radius is 6.4x106 m.

  23. Gravitational Interactions • Gravitational Field- The type of force field that surrounds massive objects. (Such as planets, moons, and stars) • Near the surface of the Earth, the gravitational field strength is 9.8 N/kg or 9.8 m/s2. • At the surface of Earth, the gravitational force on an object it the object’s weight.

  24. Gravitational Interactions To find acceleration due to gravity on any planet, use the following equation: g=GM/R2 Where G= gravitational constant, 6.67 x 10-11 M= mass of planet R= radius of planet Question: How does g at the surface of Jupiter compare with g at the surface of Earth? Data: Jupiter’s mass is about 300 times that of Earth, and its radius is 10 times greater than the radius of Earth

  25. Gravitational Field Inside a Planet • Gravitational fields exist inside planets as well as around them. • Acceleration, g, would decrease as you moved toward the center of Earth. • At the center of Earth, your acceleration would be 0 m/s2. Why? Full weight=mg Full weight=mg Half weight= mg/2 Center= weightlessness=

  26. Ocean Tides • Newton showed that tides are caused by differences in the gravitational pull of the moon on opposite sides of Earth. • The moon’s attraction is stronger on Earth’s oceans closer to the moon, and weaker on oceans farther from the moon. • How can you explain this?

  27. Tides In the Atmosphere The earth also has atmospheric tides that occur in the ionosphere. These produce electric currents that alter the magnetic field that surrounds the Earth. These “tides” regulate the degree to which cosmic rays penetrate into the lower atmosphere. This can account for subtle changes in the behaviors of living things. They are greater when the atmosphere is having its spring tides. Near the full and new moons.

  28. The sun • Two process • 1) Gravity pulling the star in • 2.) Fusion that blow solar material outward. When they balance we get a sun. If the rate increases the sun gets bigger If the rate decreases the sun gets smaller When it runs out of fuel it becomes a red giant and will be so big that it will swallow Earth. When the sun has burned all its fuel it will no longer give off heat and become a black dwarf. Black HolesFor very massive stars (2-3x more massive than the sun) that burns out, gravity takes over and become infinite. Collapse of space itself

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