Mudcat Café message #4077741 The Mudcat Café TM
Thread #132499   Message #4077741
Posted By: Nigel Parsons
01-Nov-20 - 10:54 AM
Thread Name: BS: Language Pet Peeves
Subject: RE: BS: Language Pet Peeves

Subject: RE: BS: Language Pet Peeves
From: Mrrzy
. . .
Newly discovered Triassic lizard could float underwater to pick off prey ... Well, if it is floating, it is not *under*water, now, is it?


Well, actually, they can be 'floating'. It just means that they do not need to regulate the depth of their dive. Floating is being in a state of suspension due to the upthrust of the medium one is in matching the downthrust of ones weight/mass. Or, as our physics teacher had us memorise:
"When a body is wholly or partially immersed in a liquid or fluid it receives an upthrust equal in force to the mass of liquid or fluid displaced."
Hope I got that right, it's 50 years ago now, and a quote (in translation) of Archimedes.
Divers use weighted belts to offset the floatation effect of the sea-water surrounding them.