Fatal Attraction !
In the autumn of 1912, the ocean linear Olympic, one of the world's biggest ships at the time, was steaming ahead out in the high seas, when another much smaller ship, the cruiser Hawk, rapidly approached it on a parallel course a hundred meters away.
As soon as the two ships took up a position where one pointed the other, a surprising thing happened. the Hawk sharply veered off its course, as if obeying some invisible force, turned the big liner and heedless of the helm rammed into it.The impact was so great that it made a big gash in the Olympic's hull.
A tribunal examined this queer case and found the Olympic's Skipper guilty, as, according to its ruling, he had failed to issue orders to yield the right of passage to Hawk. Consequently, the tribunal, as you can gather, saw nothing extra ordinary about it at all, attributing the the accident to the skipper's negligence.
Actually this was the result of a totally unforeseen cicumstance, a case of mutual attractions of ships at sea and the answer lies in basic physics.
Why do ships attract one another ?
As soon as the two ships took up a position where one pointed the other, a surprising thing happened. the Hawk sharply veered off its course, as if obeying some invisible force, turned the big liner and heedless of the helm rammed into it.The impact was so great that it made a big gash in the Olympic's hull.
A tribunal examined this queer case and found the Olympic's Skipper guilty, as, according to its ruling, he had failed to issue orders to yield the right of passage to Hawk. Consequently, the tribunal, as you can gather, saw nothing extra ordinary about it at all, attributing the the accident to the skipper's negligence.
Actually this was the result of a totally unforeseen cicumstance, a case of mutual attractions of ships at sea and the answer lies in basic physics.
Why do ships attract one another ?
Labels: funphysics, logic, thinktank
posted by Rajesh Lal at
11:41 PM
9 Comments:
gravity?
Bernoulli's Law. As the ships move faster relative to the water, the water between them, being squeezed by the shapes of their hulls, moves faster, than it does on the outside, and they get pulled towards each other. You can demonstrate this by holding a sheet of paper and blowing air over the top of it and observing that the paper rises.
My first thought was that the Hawk is a sailing ship, and therefore has the right of way under international laws. (because they need the wind to move)
However, the question states the Hawk is a cruiser which implies she is motorized.
My guess is that the Olympic's bow wave actually pulled the Hawk into herself.
Yh surge is right for most of it but gravity had part in it aswell as the larger mass in the olympic means a stronger force of gravity pulling the hawk in ever so slightly
On 20 September 1911, HMS Hawke, under command of Commander W.F. Blunt, collided in the Solent with the White Star liner RMS Olympic. In the course of the collision Hawke lost her prow. (This was replaced by a straight bow). The subsequent trial pronounced Hawke to be free from any blame. During the trial a theory was advanced that the large amount of water displaced by the Olympic had generated a suction that had drawn Hawke off course.
Re: gravity.
Let us assume that rather than these older and smaller ships, they were both the size of a modern aircraft carrier, a Gerald Ford Class, displacing 100K tons.
At 100m distance (as the problem states), the mutual gravitational attraction would be around 66.7 N (G*m1*m2/d^2) or about equal to gravitational pull of Earth on a 15 lb weight. Per ton of ship's weight, this is 0.0024 oz. Note that this exact force is exerted per unit of ship's weight, even if one of the ships is smaller.
Throwing feathers at your parked car is more likely to move it, than for the the mutual gravitational pull of the ships to make a difference in this scenario.
Re: larger mass. Based on the formula for gravitational pull (see earlier), two masses exert exactly equal forces on each other. Sorry, 'stronger force of gravity' will not wash. Of course, this means that I pull the Earch with about 175 pounds-force towards myself - boy, do I feel important and attactive now! :)
I did a bit of digging; Hawke was a 7350 ton vessel, the Olympic 45324 tons.
More here: http://www.euronet.nl/users/keesree/sisters.htm#Olympic
http://en.wikipedia.org/wiki/RMS_Olympic
http://www.dalbeattie.com/titanic/wmmlifeb.htm
and a discussion:
http://www.encyclopedia-titanica.org/discus/messages/5932/1062.html
The mutual gravitational attraction of these ships at stated conditions would be about a half a pound-force...
"Surge" is extremely knowledgeable.
"Bernoulli's Law" is correct. No, it's not "Gravity".
Faster moving fluid produces lower pressure. Slower fluid results in higher pressure.
Look at cross-section of airplane wings: they are shaped such that top side is longer then bottom. This creates lifting force.
Crack the window of your car. Air and cig-smoke go out (instead of wind being blown in).
This suction, due to 2 ships moving in parallel, forced Cruiser Hawke approaching Liner Olympic.
When getting closer, with Hawke pointing toward Olympic, Bernoulli's force reduced, causing Hawke to sharply point away from Olympic (the rudder did it) -- which avoided severe damages.
International Laws now enforce min 200-meter distance between 2 ships, unless BOTH speeds are reduced. (Pls correct me, if I'm wrong.)
Titanic would have "attracted" iceburg, which would make it worse. On contrary, if Captain didn't order turning away, instead, directly hitting iceburg, ship might not sink... Shark
The answer is simple:
The Olympic was like, "OMG, that little boat is as cunning as a Hawk. Olympic likey."
The Hawk was like, "Wow, that boat is so strong he could be in the Olympics."
So the reason they were brought together was the power of love.
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