Another physics question.
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Another physics question.
You are on an anchored boat at low tide.
The lantern of a lighthouse is just visible, sitting on the horizon.
At high water, with the boat in the same place, what will happen to your view of the light?
The lantern of a lighthouse is just visible, sitting on the horizon.
At high water, with the boat in the same place, what will happen to your view of the light?
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
- simonineaston
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- Location: ...at a cricket ground
Re: Another physics question.
I won't be able to see it as my seat in the pub does not face the water...
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
Re: Another physics question.
Thanks. Never seen that before.Mike Sales wrote: ↑5 Aug 2021, 12:11pm You are on an anchored boat at low tide.
The lantern of a lighthouse is just visible, sitting on the horizon.
At high water, with the boat in the same place, what will happen to your view of the light?
Is it all in one tidal system... and is there any slack in the anchor line and can you pay it out?
Jonathan
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Re: Another physics question.
Both in the same tidal system tidal system, and the boat is assumed to be in exactly the same spot.Jdsk wrote: ↑5 Aug 2021, 12:19pmThanks. Never seen that before.Mike Sales wrote: ↑5 Aug 2021, 12:11pm You are on an anchored boat at low tide.
The lantern of a lighthouse is just visible, sitting on the horizon.
At high water, with the boat in the same place, what will happen to your view of the light?
Is it all in one tidal system... and is there any slack in the anchor line and can you pay it out?
Jonathan
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Re: Another physics question.
The trouble with tidal systems is that tidal range can be very variable over such a range. So the boat might easily experience a larger tidal range than the water e.g. mid way between the boat and lighthouse.
Ian
Ian
Re: Another physics question.
Thanks, and not limited in vertical movement by the anchor?Mike Sales wrote: ↑5 Aug 2021, 12:22pmBoth in the same tidal system tidal system, and the boat is assumed to be in exactly the same spot.Jdsk wrote: ↑5 Aug 2021, 12:19pmThanks. Never seen that before.Mike Sales wrote: ↑5 Aug 2021, 12:11pm You are on an anchored boat at low tide.
The lantern of a lighthouse is just visible, sitting on the horizon.
At high water, with the boat in the same place, what will happen to your view of the light?
Is it all in one tidal system... and is there any slack in the anchor line and can you pay it out?
Jonathan
Re: Another physics question.
I didn't know the correct term for the surface all of the relevant water going up together...
Jonathan
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Re: Another physics question.
For the purposes of the question you can assume that the sea over the whole area is rising and falling by the same amount at the same time.
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
-
- Posts: 7898
- Joined: 7 Mar 2009, 3:31pm
Re: Another physics question.
No limit in vertical movement.Jdsk wrote: ↑5 Aug 2021, 12:28pmThanks, and not limited in vertical movement by the anchor?Mike Sales wrote: ↑5 Aug 2021, 12:22pmBoth in the same tidal system tidal system, and the boat is assumed to be in exactly the same spot.
Jonathan
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Re: Another physics question.
Hmmm,
> this is not an 'educated' answer by any means, but I'd guess the view of the lighthouse lantern would disappear, or be reduced
> my thinking is that yes, the anchored boat would gain height as the tide rose, but the mass of the water between the boat and lantern would also rise.
< However, the lighthouse being 'attached' to terra firma wouldn't change height, thus my answer
> this is not an 'educated' answer by any means, but I'd guess the view of the lighthouse lantern would disappear, or be reduced
> my thinking is that yes, the anchored boat would gain height as the tide rose, but the mass of the water between the boat and lantern would also rise.
< However, the lighthouse being 'attached' to terra firma wouldn't change height, thus my answer
Without my stoker, every trip would only be half a journey
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Re: Another physics question.
Correct, well thought and put.bikes4two wrote: ↑5 Aug 2021, 12:33pm Hmmm,
> this is not an 'educated' answer by any means, but I'd guess the view of the lighthouse lantern would disappear, or be reduced
> my thinking is that yes, the anchored boat would gain height as the tide rose, but the mass of the water between the boat and lantern would also rise.
< However, the lighthouse being 'attached' to terra firma wouldn't change height, thus my answer
A nautical almanac has "dipping tables".
These tabulate the distance to the horizon for various heights of eye, and for various heights of the light, or whatever.
http://www.sailtrain.co.uk/navigation/rising.htm
http://skysailtraining.co.uk/dipping_distance.htm
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Re: Another physics question.
More of a geometry question to be fair
Obviously assuming no sudden appearance of light distorting atmospheric effects.
Even if it was a lightboat and could rise in the same manner as the observer they would still lower in the horizon relative to each other.
Obviously assuming no sudden appearance of light distorting atmospheric effects.
The contents of this post, unless otherwise stated, are opinions of the author and may actually be complete codswallop
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Re: Another physics question.
The light on a lightship or buoy would remain at the same height above the sea, so its horizon would remain the same, just as the observer's would.
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
Re: Another physics question.
Yes, but the sphere they're sat on is expanding so they are getting further apart, assuming they are both rising vertically from their own perspectives, i.e. constant lat/long
The contents of this post, unless otherwise stated, are opinions of the author and may actually be complete codswallop
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Re: Another physics question.
I did consider that factor, but my feeling, with no calculation, is that the effect would be relatively infinitesimal.
It's the same the whole world over
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?
It's the poor what gets the blame
It's the rich what gets the pleasure
Isn't it a blooming shame?