The Idea of Gravitation Ideas Examples and Theories

Day 45 In APPhysics � 1) Video for next class up: You need it.

QUESTIONS TO START OFF � 1) What creates gravity? � 2) Does it have

In The Beginning �Lets talk about astrophysics �A planet and star is formed when

�In a formation event, will heavier gases be thrown farther than lighter ones? �The

�There MUST be an idea that governs pulling atoms together, planets around stars, and

�Gravity is the attraction between all masses. �It is caused by the warping of

�Idea �An 1: Gravitational Field object with mass creates a FIELD around it. �This

�When two OBJECTS are near each other, they experience each others FIELDS, and experience

�The more MASS an object has, the stronger the field. The more distance between

�Example: You are on the earth. You are the test for the Earth’s field

�Are the FIELDS of each object equal? �No! Earth has more mass, so a

�To calculate the field strength due to gravitation: �g = G(M/d 2), �where: g

�A steel sphere of mass M and radius r is now replaced by a

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The Idea of Gravitation Ideas, Examples and Theories of Gravitation and how to use it

Day 45 In APPhysics � 1) Video for next class up: You need it. � 2) Exam talk � 3) New Topic 6: Rotational and Circular Motion � 4) Today: Subtopic: Gravitation

QUESTIONS TO START OFF � 1) What creates gravity? � 2) Does it have a speed? � 3) Does it have a maximum range to be felt? � 4) Can gravity repel objects instead of attracting?

In The Beginning �Lets talk about astrophysics �A planet and star is formed when gas clouds get pulled together by gravity and become solid (or dense). �Momentum of the clouds did not change, so the formed planet/star keeps rotating

�In a formation event, will heavier gases be thrown farther than lighter ones? �The inner planets are rocky, with heavy iron cores. The iron was pulled to the middle during formation because of its larger density than the rocky silicate material.

�There MUST be an idea that governs pulling atoms together, planets around stars, and keeps them moving in orbits. �GRAVITY. The attractive force between any two objects. �Whatever Joch, I already know about gravity! That was September, before I grew bitter at

�Gravity is the attraction between all masses. �It is caused by the warping of space-time by mass itself. �Of the 4 basic forces, it is the WEAKEST

�Idea �An 1: Gravitational Field object with mass creates a FIELD around it. �This FIELD represents where another object in that region can feel a FORCE from that FIELD.

�When two OBJECTS are near each other, they experience each others FIELDS, and experience an equal FORCE towards each other. �Are the FORCES experienced by each the same? �Yes…Newtons 3 rd Law applies

�The more MASS an object has, the stronger the field. The more distance between the objects, the weaker the field. �The mass MAKING the field we call the object. The mass that feels the field is called the test.

�Example: You are on the earth. You are the test for the Earth’s field at your center of mass �And the Earth is the test for your field at the Earths center of mass �The forces are equal.

�Are the FIELDS of each object equal? �No! Earth has more mass, so a stronger field. But your small mass barely interacts with it. �The Earth’s huge mass really interacts with your weak field

�To calculate the field strength due to gravitation: �g = G(M/d 2), �where: g is the field strength/surface �G is the gravitational constant -11 6. 67 x 10 �M is the object mass �d is the distance between the

�Example

�A steel sphere of mass M and radius r is now replaced by a steel sphere that is three times the radius of the original. �Now what is the surface gravitational field?