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 Originally Posted by JKDS
For humans trying to achieve flight, why hasnt the "big bird wings, and flap em really fast" approach worked? With enough physics and the proper bird wings, why cant I literally "make like a bird" and fly over to my friend's house?
If we're too heavy, bigger wings and an engine to flap them? Pterodactyls flew though, and they were big...
Basically, it's more energetically efficient to spin a propeller in a circle, generating a constant thrust, than it is to swing a long, heavy beam back and forth (creating thrust in pulses). However, biologically, there is no such thing as an axle. So biology uses what it can, but it can't make wheels, or propellers, that only spin in one direction and never bind.
Having produced thrust, the same thing hits you with the wings of the plane. If they sit still, no energy is required to flap them back and forth. If they're the right shape, they can generate phenomenal amounts of lift.
An F/A 18 Hornet would need 8 - 10 more engines pointing down to generate as much lift as it gets from its wings. I.e., the up-force a good airfoil can generate is more than 4 times the force needed to keep it moving at a speed where it can generate such forces.
Get yourself one of these:
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TIL Pterodactylus was about the size of a bald eagle. However, Quetzalcoatlus was a Pterosaur with a 30 - 50 foot wingspan, weighing ~500 lbs.
Originally Posted by JKDS
This is an old joke / commentary. I don't know any physicist who would question the validity of the sentiment, or any mathematician who isn't at least a tiny bit smug about it. This is all brotherly love, though.
Except there is a dramatic divide between the biologists and the psychologists. Even the move from chemistry to biology is a step away from concrete cause-effect relationships most of the time.
Originally Posted by JKDS
A Mososaurous weighing 20tons (evenly distributed, lets say) and measuring 17m in length lives in a lake at a theme park. He swims into the audience viewing area, jumps halfway out of the pool to feed, and then falls back into the water.
Not unlike this: https://www.youtube.com/watch?v=Zv8qID-89ts
How big a splash/wave would the mososaurous have caused? (Height, distance traveled, and tons of water maybe?)
You guys. Not only is this so hard to put real boundaries on, 2 of you are all excited about it, so I can't as easily blow you off.
First of all, that wasn't half way. At most that was the head and not much neck, but I digress.
The short answer is: There is a huge amount of variability involved. It could be ultra-tiny, or it could be a deluge.
The amount of water displaced is pretty easy to imagine. The amount of volume is the same (or very nearly so), whether it's dinosaur or water.
Everything else is guesswork. The shape of the surface as it goes into the water makes a huge difference. An Olympic diver may leave next to no splash at all in a competition dive. I'm sure that's not the case if you could convince one to do a cannon ball.
If you jump in as though to do a canon ball, but then you thrust your legs forward just as you hit the water, you can send a large splash quite a good distance forward.
The surface tension relationship between the water and the dino's skin is going to make as much impact on splash size as the geometry of how the dino plunges into the water.
(The first few seconds is enough)
Hydrophobic: The surface tension is such that water does not stick to the surface. (a thin coating of oil would do.)
Hydrophilic: The surface tension is such that water sticks to to the surface (like water curles up a little bit at the edges in a glass cup.)
Other factors: surface debris on the water will make a big difference in the way waves propagate. That's why a nice foamy guinness doesn't slosh around and spill at parties. One more reason Guinness is the best.
If you feel like I've blown you off - well, I did. If I can find a way to postulate a maximum splash size, I'll get on it.
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