Universal Gravitation Does the moon stay at a certain distance from the Earth or is it falling toward the Earth? - the moon is actually falling around the Earth - if the moon did not fall it will continue in a straight path and fly farther and farther from the Earth

How does the moon fall around the Earth and not fall into the Earth? The harder I throw an object at the same angle the less arch it has as it is flying through the air. The moon is flying at a very fast speed so it has just a little arch toward the Earth and there is no wind resistance to slow it down so that arch does not change. In other words the moon has enough tangential velocity to avoid hitting the Earth

The Truth about Falling All objects in the universe are attracted to each other so all objects are falling toward a larger object. - all planets in our solar system are falling around the sun but will never hit the sun because they have large enough tangential velocities

Newton’s Law of Universal Gravitation Everything pulls on everything else in the universe in a way that involves only mass and distance. - the bigger the masses the more attraction between objects - the farther apart the objects are the less attraction between them

Newton’s Law of Universal Gravitation F = G m 1 m 2 / d 2 G=6.67 x Nm 2 /kg 2 Or The force of Gravity = The Gravitational Constant x the mass of the first object x the mass of the second object / the distance between the objects squared -The distance is measured from one object’s center of mass to the other object’s center of mass -Gravitational force is a very weak force

The Inverse-Square Law The farther two objects get away from each other the less gravitational force there is but how much less? -The force of gravity weakens as the square of distance. - if two objects are twice as far apart then there will be ¼ of the gravity, three times farther apart there will be 1/9 the gravity… - no matter how far out you go an object’s weight will never be zero

Gravitational Field The space around a massive object where a gravitational pull can be felt.

Gravitational Field Inside the Earth - The farther an object is inside the Earth is greater than on the surface of the Earth because the object will be closer to the Earth’s center of mass - In the middle of the Earth there is no gravity because an object in the center of the Earth is attracted to the mass of the Earth surrounding it equally on all sides.

Weight Weight is just the pull of gravity on an object’s mass - you feel more weight when you are traveling against gravity - you feel less weight when you are traveling with gravity - Free fall is an example

Weightlessness in Space Astronauts are weightless in space because they are falling toward Earth because of the pull of gravity.

Ocean Tides Ocean tides are caused by the oceans being pulled on by the sun and moon’s gravity Spring tide is when we get the highest or lowest tides because the Earth, sun, and moon are lined up Neap tides are when high and low tides are not so extreme because the sun and the moon are on opposite sides of the Earth

Black Holes A black hole in space happens when a large star collapses on itself making a very dense area with a lot of mass. - the smallest black hole has a mass 3.8 times greater than our sun but has a diameter of only 15 miles - this creates a huge gravitation field which pulls in everything around it including light - the additional matter just makes the black hole’s gravitational pull greater.

Why is the Earth Round? The Earth an all other plants are round because of gravity. Since all matter is attracted to each other through gravity, matter in space came together and compacted to create the Earth Because gravity pulls equally in all directions there are not corners in all the planets. They are all round.

Perturbation Planets revolve around the Earth because of the sun’s gravitation pull but the planets are also affect by the gravitational pull of the other planets. When two planets get closer to each other they can pull each other off their normal orbit around the sun Mayan Prophecy

The Big Bang Theory The Universe was theoretically created by a huge explosion that spread matter and created the galaxies and solar systems. At the center of where this explosion happed there is still a huge chunk of “dark matter” that did not move. The dark matter contains an estimated 73% of all the matter in the universe. - What do you think will happen to the universe eventually?