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GravityLoading...

By Jimmy HunnicuttGravity

Gravity is a force that is dependent on the mass of an object and how far away something is from that object. Gravity is the force that is responsible for why our universe is the way it is today.

The universal law of gravity

The universal law of gravity is a great discovery by Sir Isaac Newton. There is a bit of a physics legend that he came up with the idea one day while sitting under an apple tree and watching apples fall to the ground, some stories say one hit him in the head. While these stories are interesting, there was much more math involved to get to the equation we use.

The Law of Gravity

As everyone in this physics class has seen before, the value for the acceleration of gravity we use is 9.8 m/s^2, but where do we get this number from? how do we arrive at this acceleration? when you use newtons universal law of gravity you can arrive at this number when putting in the values for the radius of the Earth and its mass, you can calculate a g value for the gravitational acceleration here on the surface of the Earth. Here Fg is the force of gravity between two objects, while g is the gravity force you would feel when standing on a plant with mass m and radius r. This is why there is less gravity on the moon, because there is a smaller radius and less mass.

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Are astronauts really in zero gravity?

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Click the audio button to hear the answer!

What is happening in these pictures?

Here are a couple of visual representations of what is happening in a gravitational field. Much like a magnetic or electric field, they extend to infinity, however, most of the time the masses are far away enough that the force experienced by an object that is far away is near zero and can be ignored. This is why the moon will affect the tides, but Mars will not noticeably change the height of the sea level.