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# Gravitational Fields Question AQA PHYSICS A LEVEL watch

1. Hi, i need help with the following question:

'Two stars of mass M and 4M are at a distance d between their centres. The resultant gravitational field strength is zero along the line between their centres at a distance y from the centre of mass M. What is the value of the ratio y/d?

A: 1/2
B: 1/3
C: 2/3
D: 3/4'

i understand the method behind the answer (finding two equations for g and equating them), however i don't understand why the the common point used for the equations of g is d-y away from the 4M star, i thought it would be d+y ?
2. ???????????
3. (Original post by ithinkitslily)
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Hi! I'm sorry you've not had any replies, I'll move your thread over to the Physics forum so you can hopefully get more responses. For future reference, here's the subject forum directory
4. (Original post by ithinkitslily)
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https://www.thestudentroom.co.uk/sho....php?t=2708597
this should help you
5. As for your question about d and y, I hope this image helps...

6. (Original post by jkedwards)
As for your question about d and y, I hope this image helps...

omfg this whole time i interpreted the y to be a vertical distance i'm actually an idiot lol
thank you !

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