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Dr.Sprock
Boulder climber
Sprocketville
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Hey, how much did Dale Bard weigh?
I want to compare his Terminal V to that of say, a real gorilla like Largo?
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philo
Trad climber
boulder, co.
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DocSprock posted;
"1) rocks do break the sound barrier "
Huh? Sorry they make sound when they break but they don't break
the sound barrier.
Unless they are hurtling in from outer space.
"2)rocks can fall from the top of el cappy and never encounter wall friction"
Yup.
"3)free falling rocks will have different impact velocities depending on shape, size and density"
Nope.
"no, i am not a doctor, i'm a homo..."
OK if you say so. Not that there is anything wrong with that.
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Dr.Sprock
Boulder climber
Sprocketville
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3) Read the small print at the bottom:
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philo
Trad climber
boulder, co.
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This sounds like a job for Mythbusters.
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hobo
climber
PDX
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What is wall friction? For serious.
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Dr.Sprock
Boulder climber
Sprocketville
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Wall Friction is your Brain rubbing against your Skull after I whack you with this:
Cool for campin, it just arrived off of evilvay.
can someone Photoshop a Mumbo Special on there?
One Egg, two Bacons and 4 Sambo Cakes with Tiger Butter?
any other cool gear out there?
non REI?
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Werd
Trad climber
Bay area
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OK, I'll bite
You can actually roughly calculate the terminal velocity of a chunk of Yosemite rock to answer whether or not it will break the sound barrier...
Cd of a square = 1.05
Density of Granite ~ 2675kg/m3
Atmospheric ("gas") Density = 1.225 kg/m³ (at sea level, assuming Temp of 20C {~68F}, relative humidity of 20%)
Speed of sound ~ 340 m/s (using same conditions as above)
I chose a square for calculating drag because it's the most probable rock shape that's easy to find a Cd for; it also makes it easy to calculate it's projected surface area (have to assume the block is not tumbling).
So, just use the formula's previously posted and, voila, you have your terminal velocity of yosemite granite.
(now, does a large boulder falling off one of the walls reach terminal velocity before it hits the ground?--another calculation easily done, but I'm too lazy).
Edit to add other atmospheric pressure and speed of sound
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Dr.Sprock
Boulder climber
Sprocketville
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Gee thanks!
Knucklehead!
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tooth
Mountain climber
Guam
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corniss, that's just going to make it harder to recover the bodies.
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GDavis
Trad climber
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Was climbing on the apron friday morning and saw huge plumes of dust and debris fall off the wall and blow all the way up almost to the top of the other side of the canyon. Thing isn't done yet... pictures to be uploaded in a bit :)
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GDavis
Trad climber
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this was quite a bit later when I actually got back down to my pack to fish out the camera.
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Clint Cummins
Trad climber
SF Bay area, CA
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> Where exactly?
>
> My guess...
Actually, all that you circled is still intact. What fell was up at the right corner of what you circled. See Chris Falkenstein's photos for the details (in the section dated April 2):
http://www.myyosemite.com/
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cliffclimber
Trad climber
salem, ma
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Based on the Seismic data, the initial post in this thread misstates the time of the rockfall by nearly five hours. Check me on this people, but the seismic data backs up my earlier comment - that I heard the rockfall around 12:15. However, folks on Washington Column seem to confirm the early morning hour. Anyone got more detail on this?
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gstock
climber
Yosemite Valley
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Topic Author's Reply - Apr 6, 2009 - 02:43pm PT
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Seismic data is reported in Greenwich Mean Time (GMT), not Pacific Standard Time, so the largest rock fall did occur at 5:26 am in Yosemite Valley. However, I don't doubt that you heard a rock fall earlier that night - hoipolloi and others report hearing multiple rock falls that night prior to the largest one at 5:26 am.
I am noting all of these rock falls, and I really appreciate hearing from all of you that heard rock falls before and after the main event. Cleo and I are "listening" for rock falls both seismically and acoustically, so knowing the timing of these events is important for seeing if they show up in our data.
weschrist, the area you've circled for the rock fall source area is too big. I'm not yet photobucket savvy, but I think if you look at Chris Falkenstein's "after" photos compared to the "before" photo you can see that the source area did not extend to the summit of Ahwiyah Point as you have drawn it in. Very large rock fall nonetheless...
Greg Stock
Park Geologist
greg_stock@nps.gov
(209) 379-1420
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morphus
Mountain climber
Angleland
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rockfall air blasts can exceed the speed of sound according to this:
Results from the air blast simulations indicate that the second Happy Isles air blast (weak shock wave) traveled with an initial velocity above the local sound speed.
http://cat.inist.fr/?aModele=afficheN&cpsidt=1987361
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JEleazarian
Trad climber
Fresno CA
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Thanks Greg, Wes and all the rest. I was actually contemplating either the Harding/Merry route or something new in that area this summer, under the theory that you don't see crowds on obscurities. I guess you won't see me there, either.
John
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GDavis
Trad climber
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I kept getting spooked by the dumpster-dropping sounds eminating from the DNC.
*BOOOOOM-THUD!*
AAAAAAAAAAUGH!! I'M ON GLACIER POINT!!!!
Oh, nevermind. Just trashcans.
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Domingo
Trad climber
El Portal, CA
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GDavis: I know exactly what you mean. I honestly think they might set off avalanches.
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