# Gravitational field direction HELP!

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#1
Hey, so I've been attempting this MCQ which asks to find the gravitational field direction at a given point X

Here is the Q itself: https://imgur.com/Kyvsm2C

From what I know, equipotential are lines that show constant potential in a given gravity field.

If the field was to be radial, then the equipotential lines would be concentric circles around the centre. Where as the concentric circles get bigger, the field tends to get weaker. But this isn't the case because the figure shown in the Q has lines in going in all sorts of directions.

I know that equipotential lines always cuts the field lines perpendicularly but I can't see how they would tell the direction of the field at x.

Does the gravitational potential values given in the Q help to find the direction or not?

Thanks!
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1 year ago
#2
Equipotential lines are perpendicular to the field lines. The direction of the field is in the direction of decreasing potential.
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#3
(Original post by BobbJo)
Equipotential lines are perpendicular to the field lines. The direction of the field is in the direction of decreasing potential.
So would it look like this then?

Sorry if the image isn't clear. Don't know why the quality is so terrible.
Last edited by Yatayyat; 1 year ago
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1 year ago
#4
(Original post by Yatayyat)
So would it look like this then?

Sorry if the image isn't clear. Don't know why the quality is so terrible.
No since the field lines should point in the direction of decreasing potential. Your line points towards increasing potential
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#5
(Original post by BobbJo)
No since the field lines should point in the direction of decreasing potential. Your line points towards increasing potential
Oh okay. Got mixed up with the negative values. So it must be answer C then?
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1 year ago
#6
(Original post by Yatayyat)
Oh okay. Got mixed up with the negative values. So it must be answer C then?
Yes
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#7
(Original post by BobbJo)
Yes
Thanks a lot! Forgot about the fact that field lines point in the direction of decreasing potential.
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1 year ago
#8
I think its C

You are right that the direction of the grav field is perpendicular to the equipotentials but if you look as the gravitational potential they get increasingly more negative which means to the right delta V tends to zero and the direction of the field always starts from g=0 at infinity and tends to a more negative value.

Hope that helps
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