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Post by Verbivore on Jul 17, 2008 23:26:44 GMT
From an ABC (Oz) News Online report on the Strangford Lough sea-gen (water-powered electricity generator):
Surely "the moon's and sun's gravitational pulls"? Last time I checked, those two celestial bodies weren't married (well, not outside Babylonian and Egyptian mythology).
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Post by Paul Doherty on Jul 18, 2008 0:01:51 GMT
I'd have done it as ABC did. Causing the tides is a joint enterprise, somehow.
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Post by Verbivore on Jul 18, 2008 0:23:23 GMT
But if it's a joint enterprise (with which point I agree), surely then it should read "the moon and sun's gravitational pull" - not "pulls"?
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Post by Paul Doherty on Jul 18, 2008 0:33:00 GMT
Well, they both have a pull, and not always in the same direction, so there would seem to be two pulls going on.
I'd write Gordon and Barry's opinions, after all. (At least, I would if you were somehow acting in concert.) That's not very helpful though, because you both might have multiple opinions. Better might be Gordon and Barry's heads, but that does sound a bit like you have two each!
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Post by Bertie on Jul 18, 2008 4:35:08 GMT
A prime case for re-casting.
"[...] the gravitational pull of the sun and moon."
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Post by Vadim on Jul 18, 2008 7:45:19 GMT
A prime case for re-casting. "[...] the gravitational pull of the sun and moon." I'm with you here, Bertie. I think, after re-reading the quote with your re-cast in place, that this would avoid confusion. Things don't normally grate on me (as it's normally me that wrote them ) but the quote from ABC just doesn't read "right" for me.
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Post by Barry on Jul 18, 2008 10:40:57 GMT
I think I'm happy with it as it stands.
Am I the moon or the sun in this strange metaphor. I only show my bottom on request ...
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Post by Geoff on Jul 18, 2008 11:28:00 GMT
Well, they both have a pull, and not always in the same direction, so there would seem to be two pulls going on. However you describe it, there is one net effect of the two separate forces (pulls) exerted by the sun and the moon. I think I would prefer to say: [...] the combined gravitational pull of the sun and moon.
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Post by Paul Doherty on Jul 18, 2008 13:16:42 GMT
[...] the combined gravitational pull of the sun and moon. Works for me. But I do think the original was ok, if clumsy.
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Post by Pete on Jul 18, 2008 17:43:45 GMT
A prime case for re-casting. "[...] the gravitational pull of the sun and moon." Surely "pulls" - they each have a gravitational field!
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Post by Pete on Jul 18, 2008 17:44:31 GMT
Well, they both have a pull, and not always in the same direction, so there would seem to be two pulls going on. However you describe it, there is one net effect of the two separate forces (pulls) exerted by the sun and the moon. I think I would prefer to say: [...] the combined gravitational pull of the sun and moon. Still disagree - it has to be plural. Anyeway, I think they each cause different tides.
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Post by Tone on Jul 18, 2008 21:13:53 GMT
>Surely "pulls" - they each have a gravitational field!<
But their gravitational field is as nothing without something to pull on. (And the pull on each other.)
So the combined effect of their interacting individual fields is (singular) pull on any third body.
Tone
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Post by Paul Doherty on Jul 19, 2008 1:39:33 GMT
Disagree. The effect of two gravitational fields on a body is two vector forces. They can be mathematically combined to give the resultant vector (that is, the single force which would give the same effect) but there are still two forces involved.
If I pull you one way, and Twoddle pulls you another, you will travel as if pulled by the resultant of our two pulls. But no-one is actually applying that resultant to you: you are still subject to two actual pulls.
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Post by Geoff on Jul 19, 2008 2:30:31 GMT
Paul, Disagree. The effect is a single vector: the resultant of the two separate forces Disagree, again. You are subject to the resultant of the two separate forces. Anyway, I'm not sure what it is we are arguing here. Do you believe that the statement: [...] the combined gravitational pull of the sun and moon. would be misunderstood (and I'm not questioning you simply because the statement is what I proposed). I don't believe anyone would/could misunderstand it. If you were to say: [...] the (combined) gravitational pulls of the sun and the moon. do you not run the risk of this being interpreted as the sun exerting more than one force and the moon also exerting more than one force? How would you propose to make the statement?
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Post by Pete on Jul 19, 2008 7:59:46 GMT
Paul, Disagree. The effect is a single vector: the resultant of the two separate forces Disagree, again. You are subject to the resultant of the two separate forces. Anyway, I'm not sure what it is we are arguing here. Do you believe that the statement: [...] the combined gravitational pull of the sun and moon. would be misunderstood (and I'm not questioning you simply because the statement is what I proposed). I don't believe anyone would/could misunderstand it. If you were to say: [...] the (combined) gravitational pulls of the sun and the moon. do you not run the risk of this being interpreted as the sun exerting more than one force and the moon also exerting more than one force? How would you propose to make the statement? By recasting if necessary.
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