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gge
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If a large, stable floating object is placed in the ocean, free floating, and the tides and currents act on that object causing it to rotate, will it always rotate about its center of mass?
gge said:Thank you for the reply.
Okay, so it won't necessarily rotate around the center of the rigid object, it really depends on the distribution of the mass (the shape) of the object? One part of the object may be shaped in such a way that it generates more drag, etc.?
Won't adding a sea anchor just extend the assembly.The Earth and the centre of it's mass would in effect become part of the floating object.So it won't be rotating around the sea anchor it will be rotating around the centre of mass of the earth.jbriggs444 said:Imagine a boat which is tethered to a sea anchor. This assembly will rotate around the sea anchor, not about the center of mass of the assembly. Of course, any rotation would also be damped unless the water itself is rotating.
http://en.wikipedia.org/wiki/Sea_anchor
That is the point I am trying to make, the OP's question was about a free floating object.It is floating in and surrounded by an ocean.
Not allways a traditional sea anchor is made of metal and can go to the bottom of the sea.jbriggs444 said:A sea anchor is not made of metal and does not go to the bottom of the ocean.
A sea anchor is not made of metal and does not go to the bottom of the ocean.
Precisely. A sea anchor is a device, consisting of a bucket, drogue or anything else of neutral density (it stays just below the surface)) that will produce a drag effect when hung over the bow or stern of a boat in heavy weather. It moves the centre of pressure (underwater) well to the front or the back (depending on what you want) to keep either the bow or stern into the wind because the centre of effort ( that is the effect of wind pressure of the parts of the boat above the water) will be on the superstructure / sails and will be downwind of the sea anchor.jbriggs444 said:A sea anchor is not made of metal and does not go to the bottom of the ocean.
If a large, stable floating object is placed in the ocean, free floating, and the tides and currents act on that object causing it to rotate, will it always rotate about its center of mass?
jbriggs444 said:Imagine a boat which is tethered to a sea anchor. This assembly will rotate around the sea anchor, not about the center of mass of the assembly. Of course, any rotation would also be damped unless the water itself is rotating.
http://en.wikipedia.org/wiki/Sea_anchor
This is an textbook example of committing the very crime you accuse others of doing. You criticize others for not answering, but then do not contribute yourself.There are many ways to interpret the OP's question, which is why there are so many answers. But the upshot is that there are certainly examples involving drag that will cause a floating object to rotate about an axis other than its CoM.Steve Zissou said:Screw that. Answer the guy's question.
DaveC426913 said:This is an textbook example of committing the very crime you accuse others of doing. You criticize others for not answering, but then do not contribute yourself.
There are many ways to interpret the OP's question, which is why there are so many answers. But the upshot is that there are certainly examples involving drag that will cause a floating object to rotate about an axis other than its CoM.
If a large, stable floating object is placed in the ocean, free floating, and the tides and currents act on that object causing it to rotate, will it always rotate about its center of mass?
Imagine a boat which is tethered to a sea anchor...
Imagine a hose sprayed onto the bowsprit of a boat from the starboard side.
The stream from a hose is a current.
I think it partly depends upon what you mean by rotate.
Studiot said:Why would the side stream not just push the whole boat sideways?
The center of mass is the point at which the mass of an object is evenly distributed in all directions. It is the point where the object can be balanced.
Yes, a floating object will always have a fixed center of mass as long as its shape and composition remain the same.
The center of mass determines the axis of rotation for a floating object. The object will rotate around this point, and the rotation will be stable as long as the center of mass remains within the object.
Yes, a floating object can rotate without any external forces acting on it if its center of mass is not aligned with its geometric center. This is known as an unstable equilibrium, and any slight disturbance can cause the object to rotate.
Knowing the center of mass of a floating object is important for understanding its stability and predicting its behavior. It is also crucial for designing objects that need to float or remain stable in water, such as boats or ships.