Two by two, hands of blue. Two by two, hands of blue.

River ,'Ariel'


Natter 53: We could just avoid making tortured puns  

Off-topic discussion. Wanna talk about corsets, duct tape, or physics? This is the place. Detailed discussion of any current-season TV must be whitefonted.


Sophia Brooks - Sep 07, 2007 6:48:42 am PDT #9043 of 10001
Cats to become a rabbit should gather immediately now here

Um... my cat fell out of a second story window seemingly unhurt, however 1 week later he tried to kill me. I am not sure if proves or disproves the theory.


Nutty - Sep 07, 2007 6:49:40 am PDT #9044 of 10001
"Mister Spock is on his fanny, sir. Reports heavy damage."

I still haven't wrapped my brain about the whole "So you're driving a car at 30MPH and your headlights rake over Albert Einstein. How fast is the light going when it hits him?" question. So, yeah, counter-intuitive is the name of the game, for me.

(Actually my problem is relative motion. Dropping a basketball from a moving car, e.g., completely blew my mind with its trajectory, even after I'd viewed the whole thing as filmed with a static camera.)

somewhere around 60 stories, isn't it?

That high? That seems -- a bigger number than I would have guessed. Also, I would have guessed it was not density but, like, air-profile that determined terminal velocity. Whatever you call the difference between an ordinary squirrel and a flying squirrel with wing-y flaps extended.


tommyrot - Sep 07, 2007 6:50:45 am PDT #9045 of 10001
Sir, it's not an offence to let your cat eat your bacon. Okay? And we don't arrest cats, I'm very sorry.

OK, a quick explanation of the car thing. A car that's moving at 25 mph actually is at a disadvantage when it comes to acceleration compared to a car at rest. Assuming a one-speed transmission, the engine is already turning pretty fast, meaning it's completing more cycles and burning more fuel. So the engine has to go faster and faster, completing more and more cycles, burning more and more fuel in the same space of time as the car approaches 50 mph. Hence the consuming four times the energy to get to 50 mph.

Has what I've said made sense? Does the whole thing just weird you out with the unintuitiveness? Or is it just seem too abstract and "mathy" to get that feeling?

I'm wondering what Nilly and Gud would think....

The subject combines two areas of fascination to me - math/physics, and the human brain's intuitive understanding of how the world/reality works. 'Cuz the two are often at odds.


meara - Sep 07, 2007 6:51:04 am PDT #9046 of 10001

My friend had her cat fall out a six story window (or was it 8? I've now forgotten, dang!) and survive.


Nutty - Sep 07, 2007 6:54:58 am PDT #9047 of 10001
"Mister Spock is on his fanny, sir. Reports heavy damage."

Also, how do you test and remain even vaguely ethical?

I was going to say, based on my watching of Animal Cops, I bet there is enough anecdotal evidence to provide at least a reasonable conjecture.

Assuming a one-speed transmission, the engine is already turning pretty fast,

But... aren't cars not actually one-speed? You ride around in a car, you get used to hearing the engine change pitch as it accelerates. (Even an automatic like mine!). I think that using a one-speed bike would be a less confusing/more intuitive explanation.


Vortex - Sep 07, 2007 7:02:00 am PDT #9048 of 10001
"Cry havoc and let slip the boobs of war!" -- Miracleman

I'm not willing to get up at the buttcrack of dawn for an office. I have skewed priorities.

that is a super tough one for me. Depends on how much time, I guess.


tommyrot - Sep 07, 2007 7:02:30 am PDT #9049 of 10001
Sir, it's not an offence to let your cat eat your bacon. Okay? And we don't arrest cats, I'm very sorry.

But... aren't cars not actually one-speed? You ride around in a car, you get used to hearing the engine change pitch as it accelerates. (Even an automatic like mine!). I think that using a one-speed bike would be a less confusing/more intuitive explanation.

Yeah, that's true. Considering a multi-speed transmission makes it more complicated, which makes the intuition more difficult to chase about.

The short answer is that having the transmission shifting during the acceleration makes no difference (assuming the engine is equally efficient at different RPMs, which actually is not the case). A transmission picking a different gear ratio is just a sort of tool (in the classical physics sense). If you use a lever to increase the amount of motion of the one end of a fulcrum as you push the other end, you're not actually using less energy to move an object further, as you would need to use more force as you push down. A tool (in the classical physics sense) doesn't give you more energy, it just trades force for distance to give you an advantage in moving something. Like, if you use a lever to move something with less force, you'll have to push your end of the lever further, so the total energy to move the object is the same. The same principal applies to different gear ratios in a transmission.

Bah. I am trying to make the explanation short, but I think I should be more detailed. But I really should do some work today too....


sarameg - Sep 07, 2007 7:03:52 am PDT #9050 of 10001

It isn't just getting the feet under them, it's the time it takes their bodies to relax to absorb the shock of landing.


Lee - Sep 07, 2007 7:05:04 am PDT #9051 of 10001
The feeling you get when your brain finally lets your heart get in its pants.

My itunes just played On the road again and now I have to leave for work.

I think the earworm is going to be massive and unavoidable.


Kathy A - Sep 07, 2007 7:10:40 am PDT #9052 of 10001
We're very stretchy. - Connie Neil

Goin' places where I've never, ever been
And I can't wait to get on the road again...

Hec, don't look!

But you can look at this.