Key Concepts
* Newton's Law of Universal Gravitation: This law states that every object in the universe attracts every other object with a force that is:
* Directly proportional to the product of their masses: More massive objects exert a stronger pull.
* Inversely proportional to the square of the distance between their centers: As objects get farther apart, the gravitational force weakens rapidly.
Calculating the Difference
1. Earth's Radius: The Earth's radius is approximately 3959 miles.
2. Distance from Earth's Center:
* At the surface: 3959 miles
* 100 miles above the surface: 3959 + 100 = 4059 miles
3. Force of Gravity Calculation: The force of gravity (F) can be calculated using the following formula:
* F = (G * m1 * m2) / r^2
* G = Gravitational constant (6.674 x 10^-11 N m^2/kg^2)
* m1 = Mass of Earth (5.972 x 10^24 kg)
* m2 = Mass of an object (we can assume a standard mass for comparison)
* r = Distance between the centers of the Earth and the object
4. Comparison:
* You'll find that the force of gravity at 100 miles above the surface is significantly weaker than at the surface. Because the distance (r) in the formula is squared, a relatively small change in distance leads to a more pronounced change in the force of gravity.
Important Note: The force of gravity never truly reaches zero. It weakens as distance increases, but it theoretically extends infinitely. However, at extreme distances, it becomes practically negligible.
Practical Example:
* Satellites orbiting the Earth experience a weaker force of gravity than objects on the surface. This is why they can stay in orbit without falling back to Earth.
In Summary: The force of gravity at 100 miles above the Earth's surface is noticeably weaker than at the surface. This is because the distance between the object and the center of the Earth increases, and the force of gravity is inversely proportional to the square of the distance.
