Wrathchilde
Wrathchilde t1_j7hepvd wrote
Reply to Is there a term for lake bottoms that "hour glass" (temporarily becomes wider following a "shelf" as the depth increases ) , how do bathymetric maps depict this, and does this have a common affect on turbidity, thermoclines, or other characters? by Irisgrower2
Bathymetric mapping techniques using either sonar or the interesting "rope with a weight on the end" method you mentioned do not capture overhanging features well. You would need to collect 3-D data like with an AUV or ROV to produce a model, and a standard bathymetric projection map would not be able to display it in any case.
I have been in a submersible and encountered large overhangs not shown on maps even in areas that have extensive data. It's unnerving.
Wrathchilde t1_j16qem6 wrote
Reply to comment by Liveware_Failure in Modifying the volume modifies the buoyancy of a body? by wr0ttit
>but with current materials you'd struggle to get anything more than a tiny amount of bouyancy from the second example
This is the principle used to propel Autonomous Underwater Vehicles (gliders)
Wrathchilde t1_jaxn6eg wrote
Reply to How is it that objects in equilibrium stay in motion at constant velocity? by KWOOOSH
That which you think of as "at rest" is actually in motion. That glass on the coffee table is moving at 1000 km/hr as the earth rotates (relative to the center of the earth and depending on your latitude). Everything on earth is moving at 30,000 m/s relative to the sun... etc.
Only change in motion requires an external force, otherwise, everything just cruises along.