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Author Topic: Velocity of falling objects with differing mass and profile  (Read 571 times)

sneoh

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Since I was the one who first mentioned terminal velocity, I feel compelled to start a new topic and attempt to set a few things straight.

These are two good sites (be sure to read all of it, not just part of the articles) -
http://www.grc.nasa.gov/WWW/k-12/airplane/termv.html
http://www.ehow.com/list_5761172_ball-drop-science-projects.html

Fact:
Over a short distance of 10 feet, spherical balls of different size, mass, and density will hit the ground at the same time.
If one were to drop a pigeon's feather and a 14lb bowling ball off the Brooklyn Bridge, the bowling ball will hit the water first.


And I believe (going by the equation from the NASA site), a 14lb bowling ball will have a higher terminal velocity than a 1 oz ping-pong ball when dropped from the tallest building in the world.  This is because the equation for terminal velocity V = sqrt (2*mass*G/(Cd*rho*area)) means that V is proportional to sqrt(density*radius of ball) since mass is proportional to density * radius ^3 and area is proportional to radius^2 and Cd for both balls are about the same.
Hence the bowling ball should hit the ground before the ping  pong ball, assuming at least the ping pong ball has reached terminal velocity.

Though I have not practice mechanical engineering the past 15 years, having a Master degree in ME specializing in Fluid Mechanics and Thermodynamics does come in handy at times when I have the discipline NOT to shoot from the hip and say stupid things like a human reaching terminal velocity after 230 feet.  NOT.

Flame on.
« Last Edit: May 25, 2013, 09:53:52 PM by sneoh »
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"You have to decide to do a flag, where you can broke your vertebrae or a barn door depending of your pro" - the poster formerly known as Champ

danf

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Re: Velocity of falling objects with differing mass and profile
« Reply #1 on: May 25, 2013, 09:06:39 PM »

I'm just a hole digger and occasional professional wheelbarrow driver.  My physics understanding and comprehension is limited by what I remember from high school, and with a hot teacher like Ms. Jordan at the front of the class it's amazing that I remember anything that she was actually trying to teach....  No flames from me.  ;D
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strandman

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Re: Velocity of falling objects with differing mass and profile
« Reply #2 on: May 25, 2013, 09:09:08 PM »

Nice S-- fluid dynamics helps the drinking !  Is F=MA done ?

A long fall generates a lot of force AND hurts- this is my theory and i'm stickin' with it.
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strandman

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Re: Velocity of falling objects with differing mass and profile
« Reply #3 on: May 25, 2013, 09:10:24 PM »

I'm just a hole digger and occasional professional wheelbarrow driver.  My physics understanding and comprehension is limited by what I remember from high school, and with a hot teacher like Ms. Jordan at the front of the class it's amazing that I remember anything that she was actually trying to teach....  No flames from me.  ;D

danf- maybe she could have taught you ' fluid dynamics"   8)
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danf

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Re: Velocity of falling objects with differing mass and profile
« Reply #4 on: May 25, 2013, 09:16:56 PM »

I would have loved to have had a lesson or two! LOL!
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DGoguen

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Re: Velocity of falling objects with differing mass and profile
« Reply #5 on: May 25, 2013, 09:37:10 PM »



I had sister Mary Madeline for physics.
Don't ask.
« Last Edit: May 26, 2013, 08:37:20 AM by DGoguen »
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sneoh

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Re: Velocity of falling objects with differing mass and profile
« Reply #6 on: May 25, 2013, 09:40:27 PM »

John, as more common than not, you are spot on as it relates to climbing.  Moral of the whole thing - try not to take long falls but if unavoidable use a dynamic rope. 
How about them Bruins? :)
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strandman

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Re: Velocity of falling objects with differing mass and profile
« Reply #7 on: May 26, 2013, 09:45:29 AM »

Maybe we should discuss the Ablokov Cams ? no fuck it

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sneoh

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Re: Velocity of falling objects with differing mass and profile
« Reply #8 on: May 26, 2013, 12:36:18 PM »

This - http://cascadeclimbers.com/plab/showphoto.php?photo=6591&title=ablokov-cam&cat=504 ?
Looks like a 'vintage' Tri-Cam.  And, John, we ALL know HOW MUCH you love them Tri-Cams!
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Admin Al

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Re: Velocity of falling objects with differing mass and profile
« Reply #9 on: May 26, 2013, 04:09:38 PM »

Moral of the whole thing - try not to take long falls but if unavoidable use a dynamic rope. 

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kenreville

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Re: Velocity of falling objects with differing mass and profile
« Reply #10 on: May 26, 2013, 05:57:33 PM »

Ha! I was an ME major until I took fluid dynamics. Although I did quite well for me in that class (a B+), I switched my major after that term to electrical engineering (BSEE). Never looked back! Left the world of pumps, valves & fittings to understand other things like transistors, power semi-conductors, and industrial control (which is what I do these days).
Funny thing is- you can't divorce yourself from either discipline in the real world. Although I have a pretty good understanding of electricity, I regularly deal with many "mechanical" issues. Like pumps, valves, and fittings. Go figure?
« Last Edit: May 26, 2013, 06:00:47 PM by kenreville »
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sneoh

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Re: Velocity of falling objects with differing mass and profile
« Reply #11 on: May 26, 2013, 06:06:59 PM »

I have always figured ME is good background for many "real life' things.  And proven right a number of times. 
I've fully crossed over to the dark side of designing and writing software.  Go figure!
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kenreville

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Re: Velocity of falling objects with differing mass and profile
« Reply #12 on: May 26, 2013, 06:13:18 PM »

I have always figured ME is good background for many "real life' things.  And proven right a number of times. 
I've fully crossed over to the dark side of designing and writing software.  Go figure!

So you have a master in ME, and you're designing and writing software?

I don't know you sneoh- but I do know that if we ever do meet, we're gonna get along just fine.

Smart effers unite!
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sneoh

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Re: Velocity of falling objects with differing mass and profile
« Reply #13 on: May 26, 2013, 06:27:26 PM »

Yeah, Ken. Funny twist of fate; I've worked for a great company the last 15 years, really enjoy what I do most of the time, and appreciate the attitude, intelligence, and dedication of the people I work with and for.

It would be my pleasure if our paths were to cross, Ken.  And as I said in another post, if I get my good form and shape back, I would love to give The Promised Land a try (having done Vultures, Romper Room, and Bette Noir there, and failing miserably on Eyeless).  Feel free to spray me down with route Beta; I've been a sport weenie for many years now and have no pride :)

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kenreville

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Re: Velocity of falling objects with differing mass and profile
« Reply #14 on: May 26, 2013, 06:34:56 PM »

I seconded the Promised Land with Andy Ross on the first ascent. We gave it easy 5.12. The only time I climbed the route was that day.
I'm told a hold broke after we climbed it and upped the ante to hard 5.12.
Lots of brain cells have sizzled since that day- can't say I could give you any beta.
Regardless, we can still swill beers anytime.
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