Positive value for gravitational field strength?

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Fross877
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Explain why the resultant gravitational field strength changes from a negative value near the earth to a positive value near the moon?

Because its changed sign, is the answer that the field strength is now acting towards the moon as opposed to the earth?
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BTAnonymous
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I think it's to do withe the work being done against earth's gravity? when an object is moving against earth's gravity, gravity is doing negative work but when the object reaches the influence of the moon's gravity, positive work is being done by the moon and no work is being done by earth.

purely speculation so don't take my answer as correct.
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adsuudixfra
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the overall effect of the gravitational field due to both the moon and the earth is, at that point, to pull the object away from the earth, so the potential becomes positive when r is the distance from the earth
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Eimmanuel
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(Original post by Fross877)
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Explain why the resultant gravitational field strength changes from a negative value near the earth to a positive value near the moon?

Because its changed sign, is the answer that the field strength is now acting towards the moon as opposed to the earth?
Not sure what you mean by now?

Assume the Earth is at the origin and the moon is somewhere on the positive x-axis say +xm.
Along the points between the origin and +xm :
The gravitational field strength vector due to the Earth is always pointing to the left or toward the origin.
The gravitational field strength vector due to the moon is always pointing to the right.

The resultant gravitational field strength at a point is the vector sum of the gravitational field strength vector gE due to the Earth and gravitational field strength vector gM due to the moon.

So the resultant gravitational field strength can change from a negative value (|gE| > |gM|) near the earth to a positive value (|gE| < |gM|) near the moon .
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Fross877
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(Original post by Eimmanuel)
Not sure what you mean by now?

Assume the Earth is at the origin and the moon is somewhere on the positive x-axis say +xm.
Along the points between the origin and +xm :
The gravitational field strength vector due to the Earth is always pointing to the left or toward the origin.
The gravitational field strength vector due to the moon is always pointing to the right.

The resultant gravitational field strength at a point is the vector sum of the gravitational field strength vector gE due to the Earth and gravitational field strength vector gM due to the moon.

So the resultant gravitational field strength can change from a negative value (|gE| > |gM|) near the earth to a positive value (|gE| < |gM|) near the moon .
Thank you that makes a lot of sense now compared to my original thoughts
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