The Naked Scientists

The Naked Scientists Forum

Author Topic: Physics of freefall  (Read 17631 times)

Offline Rach217

  • First timers
  • *
  • Posts: 2
    • View Profile
Physics of freefall
« on: 12/12/2002 03:32:40 »
I was wondering if anyone knew that if you were to jump off a building, would you die of fright before the ground or just die on impact? A friend and I were discussing it, and I heard that you died of fright, and I bet him $10 I was right. So hopefully I'm right. Thanks a lot!
« Last Edit: 14/03/2004 05:29:36 by NakedScientist »


 

Offline Rach217

  • First timers
  • *
  • Posts: 2
    • View Profile
Re: Physics of freefall
« Reply #1 on: 16/12/2002 20:52:00 »
ok people..please put your thought or imput into this! i need that extra $10 to buy christmas presents!!
 

Offline NakedScientist

  • Moderator
  • Sr. Member
  • *****
  • Posts: 355
    • View Profile
    • http://www.thenakedscientists.com
Re: Physics of freefall
« Reply #2 on: 23/12/2002 08:19:31 »
Sorry Rach - I'd start sweetening up your mate in the hope that they are willing to spend some of your $10 on you !

We don't think that the majority of people do die of fright, but rather of 'terminal deceleration trauma', upon hitting the deck !

BUT, under extreme stress people can trigger abnormal heart rhythms (dysrhythmias) (usually people with an underlying cardiac problem) which can render them unconscious, or even dead, so it is possible that the stress of jumping could trigger such a rhythm, causing them to be unconscious prior to terminal impact. Unfortunately this is a rather difficult (not to mention unethical) hypothesis to test.

The best evidence that comes to mind would be to look at people doing parachute jumps for the first time. Whilst broken legs are not unusual, most people don't die of fright (that we know of !). The same goes for stunt artists and divers who jump from cliff edges and high boards.

Merry Christmas

TNS
 

Offline paulat

  • New Theorists
  • Jr. Member
  • *
  • Posts: 44
    • View Profile
Re: Physics of freefall
« Reply #3 on: 23/12/2002 08:23:49 »
I'll agree to agree with you Rach, if you agree to split the winnings !

I have to say though that if you look (god forbid) at the images of people jumping from the World Trade Centre following the tragic terrorist attacks last year, many of those people were clearly moving (in terror) on the way down, so I don't think you die of fright when falling.

Also, when you get into other terrifying situations - getting mugged, ending up in a field with a bull, meeting the mother-in-law for the first time, you don't die of fright, so what should be different about jumping off a building ?

Paula
 

Offline Exodus

  • Phileas Fogg
  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 1471
  • Geology
    • View Profile
Re: Physics of freefall
« Reply #4 on: 09/01/2003 13:37:35 »
What if the building was a garden shed? would such an impact kill you, prob not, more likely a nice rusty fork left out by my mum would do the trick... [xx(] she swung a shovel round once and i happened to hit it...[B)]

Thats Economics...
« Last Edit: 09/01/2003 13:38:33 by Exodus »
 

Offline pat

  • Jr. Member
  • **
  • Posts: 47
    • View Profile
Re: Physics of freefall
« Reply #5 on: 09/01/2003 18:08:01 »
Do they have computers in Uzbekistan ?!! Are they on the internet ? That's not economics...that's scary !

Surely it doesn't matter what you actually hit on the ground, it's still an impact isn;t it ?

Pat.
 

Offline Exodus

  • Phileas Fogg
  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 1471
  • Geology
    • View Profile
Re: Physics of freefall
« Reply #6 on: 11/01/2003 12:50:29 »
I bought my computer in Kazakhstan as they are a bit ahead of us in technology. I use a russian built sattelite link up system to transmit onto the web, you should see my room, cables everywhere.

As for your view on impacts... yes its an impact, but the height of a garden shed would not give your body enough time to accelerate to terminal velocity. This is the maximum speed you reach within freefall. For example, a skydiver is known to have a terminal velocity (with chute closed) of about 200 km/h, which is around 124 miles an hour (54m/s).

Also:
The more compact and dense the object, the higher its terminal velocity will be. Typical examples are the following: raindrop, 25 ft/s, human being, 250 ft/s.

(Bueche, Fredrick. Principles of Physics. New York: McGraw Hill, 1977: 64.)

Thus if you jump froma high building then when you impact, you will be close to the terminal velocity. This wouldn't be the case from jumping from a shed, hence you wouldn't die unless there was a rusty fork or rake on the floor or something... ;)

Thats Economics...
 

Offline pat

  • Jr. Member
  • **
  • Posts: 47
    • View Profile
Re: Physics of freefall
« Reply #7 on: 11/01/2003 16:25:31 »
Nicely put, thanks. Reassuring to know that the terminal velocity of a skydiver approaches 124 mph...with the chute CLOSED ! And there was me worrying for a minute that that was the speed with chute deployed !!

By the way, why do you assume that a rusty fork of rake lying on the floor would kill you ? If you've had a tetanus jab you should be alright. Unless a fork or rake prong somehow went into your eye I suppose...nice.

Pat
 

Offline Donnah

  • Ma-Donnah
  • Neilep Level Member
  • ******
  • Posts: 1756
    • View Profile
Re: Physics of freefall
« Reply #8 on: 12/04/2003 18:35:47 »
Well, you've probably heard the expression "it's all fun and games until someone loses an eye.....then it's a sport"[B)]!  As for the ft/s being an outdated mode of measure, do they not still use Imperial measure in the U.S.?

Rach, I'm sorry but I have to side with your friend.  I made a parachute jump, and from the time I left the airplane until I hit the static line I was so terrified that I cannot recall it, though my instructor said I went into a perfect arch.  Once the chute opened it was unbelievably fantastic; until I hit the ground.  It didn't feel like the parachute slowed me down at all, and I limped on both legs for about three weeks, but I'm alive (in case you didn't know).  That being said, I'm glad I did it:D.  

I didn't hit any rusty forks or rakes when I landed, but then my mother wasn't there.
« Last Edit: 12/04/2003 19:00:14 by Donnah »
 

Offline NakedScientist

  • Moderator
  • Sr. Member
  • *****
  • Posts: 355
    • View Profile
    • http://www.thenakedscientists.com
Re: Physics of freefall
« Reply #9 on: 13/04/2003 23:29:34 »
Not sure about ft/s in America, but in Britain we pride ourselves on being metric, except for bananas on fruit stalls and hash !

As Ali G said "schools need to modernise and teach things in eighths and sixteenths", or something like that !
 

Offline Quantumcat

  • The Kitty Down Under
  • Hero Member
  • *****
  • Posts: 894
    • View Profile
Re: Physics of freefall
« Reply #10 on: 21/04/2003 14:57:13 »
"The world will turn metric ... just you wait and see! Except for those stubborn yanks." - My Dad
 

Offline chris

  • Neilep Level Member
  • ******
  • Posts: 5339
  • Thanked: 65 times
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
Re: Physics of freefall
« Reply #11 on: 21/04/2003 19:18:01 »
I don't know, we're still using miles and miles per hour in the car, although we're buying petrol in 'litres' these days. Interestingly lots of garages started to sell fuel solely in litres way before the official ruling made it law to do so. This co-incided with some mega hikes in fuel prices, so it was a convenient way for them to mask the rising cost of fuel.

Chris
 

Offline Donnah

  • Ma-Donnah
  • Neilep Level Member
  • ******
  • Posts: 1756
    • View Profile
Re: Physics of freefall
« Reply #12 on: 21/04/2003 20:42:58 »
American made cars?  Maybe cars targeted at the American market.
 

Offline bezoar

  • Hero Member
  • *****
  • Posts: 950
    • View Profile
Re: Physics of freefall
« Reply #13 on: 14/03/2004 14:37:15 »
We still sell our fuel in gallons, and I'll bet it's cheaper than yours.  Just filled up yesterday, and the price is climbing -- $1.53 a gallon.
 

Offline tweener

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 1144
    • View Profile
Re: Physics of freefall
« Reply #14 on: 15/03/2004 22:15:34 »
I thought everyone except the US used metric for almost everything.  Our schools have screwed up the metric system completely by making it a "required" subject and then only teaching how to convert from one to another.  Everyone hated it, there was never a prayer of understanding what a "meter" or "liter" (or anything else) really meant.  Since then (30 years ago) no one here wants anything to do with the metric system.

In engineering school, everything was taught in metric, and it makes it so much easier.  The few profs that would teach in imperial units made me really appreciate metrics.

Hey, Nancy, I want some of that cheap gas!  It's $1.67 here.  And climbing.

Maybe if the prices climb any higher, they'll mask it by going to liters.

----
John - The Eternal Pessimist.
 

Offline Exodus

  • Phileas Fogg
  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 1471
  • Geology
    • View Profile
Re: Physics of freefall
« Reply #15 on: 17/03/2004 16:47:26 »
speaking of fuel prices, i just got back from the canary islands and i couldn't believe the price of petrol compared to here. It was 43 Euro Cents per litre!!! Just shows how much the bloody UK government is skimming of the top eh?

Christopher, i only just got your voicemail concerning my visit to Oz as i only got back from the field trip yesterday! Was a good trip apart from getting my face burned on my descent from the summit to the ground! that was quite an experience. We hiked a 5 hour trip and did the equivalent of walking from the top of Ben Nevis across Lava Fields and pumice... hold on, let me find a picture of it, its an amazing volcano...



you can see how clearly it stands out on the satellite view as well!



  Awesome!

Resident Tour Operator - The Naked Scientists
 

The Naked Scientists Forum

Re: Physics of freefall
« Reply #15 on: 17/03/2004 16:47:26 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums