How to Calculate Gravitational Field Strength at 400000m from Earth?

In summary, the Earth's gravitational field strength at a height of 400000m is -8.4 mega Newtons per kilogram, calculated using the formula F_G/m = -GM/r^2, taking into account the distance from the center of the Earth rather than the height above the surface. The notation used in the first paragraph is unclear and the original poster failed to get the correct answer using V/r.
  • #1
Harmony
203
0
Distance form the Earth's surface: Gravitational potential/MJkg-1
0 : -62.72
400000 : -59.12

Deduce the Earth's gravitational field strength at a height of 400000m.

Since g=-GM/r^2 and V=-GM/r , I tried to solve this question using V/r. But I failed to get the correct answer. Any suggestion on how to approach the question?
 
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  • #2
I don't understand your notation in the first paragraph.

However, be sure to use the distance from the center of the Earth in your calculation (and NOT the height above the surface)!
 
  • #3
The gravitational field is given by
[tex]F_G/m=-\frac{GM}{r^2}[/tex]
so at the surface it is [itex]-9.8[/itex]
and at the required distance [itex]-8.4[/itex] mega Newtons per kilogram.
 
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FAQ: How to Calculate Gravitational Field Strength at 400000m from Earth?

What is gravitational strength?

Gravitational strength is a measurement of the force of gravity between two objects. It is determined by the mass and distance between the objects.

How is gravitational strength calculated?

Gravitational strength is calculated using Newton's Law of Universal Gravitation, which states that the force of gravity is directly proportional to the product of the masses of the objects and inversely proportional to the square of the distance between them.

What factors affect gravitational strength?

The two main factors that affect gravitational strength are the mass of the objects and the distance between them. Greater mass and shorter distance result in a stronger gravitational force.

What is the unit of measurement for gravitational strength?

Gravitational strength is typically measured in units of newtons (N) or pounds (lbs).

How does gravitational strength differ on different planets?

Gravitational strength differs on different planets due to variations in mass and distance. Planets with greater mass and smaller sizes will have stronger gravitational strength, while planets with smaller mass and larger sizes will have weaker gravitational strength.

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