Gravity

Hey everyone!

Thanks to the first few people who've joined this blog!

Today, I thought that we could spend some time talking about the force of gravity and gravitational fields, because that's a pretty important topic that we weren't able to cover in class.

Gravity is the weakest intermolecular force... it really is ADORABLE compared to all the others.

What the heck IS a gravitational field?


Simply put, a gravitational field is the force a body applies on another body per unit mass of the second body. Every object generates a gravitational field around itself- this field has an INFINITE area. Basically, every object in the universe applies a force on every other object in the universe.

So why can't I fly to Pluto right now? Why don't I feel a force pulling me towards people in the halls at Interlake? Why don't my empty soda cans throw themselves into the trash can?

The force that two objects apply on each other is dependent on two factors:
1) Mass: Basically, the larger two objects are, the greater the force they will apply on each other. The mass of  an object and the force that it applies on another object are directly proportional. Relatively speaking, my soda can has very little mass, especially compared to a really heavy object like a star! This means that the soda can and the Sun don't apply very much force on each other. If I somehow managed to get a soda can as massive as the moon, the Sun would have to apply a much greater force on it to keep it in orbit.

2) Distance: The best way to explain this idea is with magnets. The further two magnets are from each other, the easier it is to hold them apart, right? So you can say that the magnets apply less force on each other the farther apart they are. The same concept holds true for gravitational force between two objects Vs. the distance between them. Gravitational force is inversely proportional to the distance^2 between two objects.   That's why Mercury travels so much faster around the Sun than Pluto- Mercury is much closer to the Sun, so the Sun applies a greater force on it. This means that it has a greater velocity as it orbits the Sun.

How can all of these ideas be used to make a single general equation?

What this means is that the force between two bodies is equal to the product of the masses of the objects * the universal gravitational constant / (the distance between them^2).

As always, if you have a question or comment, post here or send me a facebook message!