How does distance affect the size of the gravitational pull?

Question

I really need help with this question, it's for a physics project in for Thursday, n i just dont know!! Help!

Answer 1

Hi. Generally, the farther an object is from the Earth, the lower is the gravitational pull. The actual formula for the weight (which is a Force of Gravity) is:

F(Weight)= {G*mass1 x mass2}/r^2,mass is in kilograms, G is called the gravitational constant (6.67e10^-11), and r is the distance in meters, so r^2 is distance squared.

The "r" here is actually referring to some imaginary distance from a finite "point", but the Earth isn't just one point (it has a diameter of thousands of miles). So when we calculate for gravitational force, the "r" actually refers to the distance from the center of the Earth to the surface where the object rests. Don't make the mistake of assuming that the distance starts at the surface of the Earth. If I have one object at sea level and another at 10,000 meters above Earth, the gravitational pull on both is about the same because the distance from the center of the Eart to sea level and the distance from the center to 10,000 feet isn't too different. It's like adding a rather small number to a really large one (the distance from surface to center of the Earth).

However, there is a small difference because an object 10,000 meters up is still farther from the Earth's center, and so there is a slightly lower gravitational pull on it.

All objects that have mass attract each other with some force, however small. In fact, by using the above formula you can calculate that force. Use the distance from the center of mass of each object to the other as "r". You'll get a really really small number, but the force that they each have on the other becomes smaller and smaller in proportion to the square of the distance from each other. That is:

If I have two objects of equal mass, initially at 2 meters "r" distance, and I pull them away from each other to 4 meters, I have doubled the distance "r", but I have made the force smaller by a factor of 4 (since I square 2). If the objects are 3 meters apart initially and I pull them to 6 meters apart, the force will be lowered by 4 (2 squared).

So find out by which factor the distance is changed. Say you double the distance, so the factor is 2. Then square it, 2^2=4, and 4 represents the factor by which gravitational force is lowered. That is, the force is now 1/4th of what it was initially. Here are some examples

OriginalDistance (between two points): 2meters
NewDistance: 6meters
Factor: 3 (I multiplied 2 by 3)
The New Gravitational Force is: 1/9th of the original
Notice you don't have to go through the chore of mass, G, etc. Just use the factor by which distance was changed, square it, and do one over that as the new gravitational force.

Answer 2

As the distance between 2 objects increases, the gravitational pull between them decreases in proportion to the distance squared. I know that didn't help, so here is an example.
Suppose the original gravitational force between two objects is 100 Newtons.
If the distance DOUBLES, the resulting force is 100 times 1/2 squared, which is 100 times 1/4, or 25 Newtons.
If the distance TRIPLED instead of doubling, the resulting force would be 100 times 1/3 squared, which is 100 times 1/9, which is eleven and one ninth Newtons.

Answer 3

The further you move away the less the pull. An interesting note is the moon controls our gravity. If the earth was just 5 miles more away from the moon that would effect sea level tremendously. Look it up on the net, search for Newtons laws of gravity