# Universal Gravitation and magnitude

• Dgolverk
In summary, the magnitude of the force of gravity acting on a 340 kg satellite 850km above Earth's surface is 187,701N. However, the correct answer is 2.1E2N, which is likely due to an error in using the distance between the satellite and Earth's surface instead of the distance between their centers. Using the correct distance, the force of gravity can be calculated accurately using the Universal Gravitation Law.
Dgolverk

## Homework Statement

Determine the magnitude of the force of gravity acting on a 340 kg satellite, 850km above Earth's surface.

## Homework Equations

So I dedcided to use the Universal Gravitation Law:
Fg = (Gm1m2)/d^2

## The Attempt at a Solution

m1=5.98E24 (earth's mass)
m2=340kg (satellite)
G=6.67E-11
d=850,000m

After subbing them all into the formula I got 187,701N.
However the answer in the book is 2.1E2N.
So I'm not sure if I did it right... can you please check it?
Thanks

Dgolverk said:

## Homework Equations

So I dedcided to use the Universal Gravitation Law:
Fg = (Gm1m2)/d^2
Good choice. But the distance "d" is between the centers of the two bodies, not height above the Earth's surface.

Oh.. I see.
So how can I continue? I'm not really sure what to do next...

You're given the distance between the satellite and the Earth's surface. What's the distance from the Earth's surface to the Earth's center--the radius of the Earth? (Look it up!)

Alright I understand.
Thanks :)

## 1. What is universal gravitation?

Universal gravitation is a scientific law discovered by Sir Isaac Newton, which states that every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

## 2. How is the magnitude of gravity measured?

The magnitude of gravity is typically measured in units of acceleration, such as meters per second squared (m/s^2) or feet per second squared (ft/s^2). It can also be measured in units of force, such as Newtons (N) or pounds (lbs).

## 3. What factors affect the magnitude of gravity?

The magnitude of gravity is affected by two main factors: the masses of the two objects and the distance between them. The larger the masses of the objects, the greater the gravitational force between them. And the farther apart the objects are, the weaker the gravitational force becomes.

## 4. Why is gravity considered a universal force?

Gravity is considered a universal force because it affects all objects in the universe, regardless of their size or composition. It is responsible for the motion of celestial bodies, the formation of galaxies, and the behavior of matter on a microscopic level.

## 5. How does the inverse square law apply to universal gravitation?

The inverse square law is a mathematical representation of how the strength of gravity decreases with distance. It states that as the distance between two objects increases, the force of gravity between them decreases by the square of that distance. This means that the farther apart two objects are, the weaker their gravitational attraction will be.

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