Falling down

Post by **ynot** » Mon Feb 24, 2003 1:38 am

We were discussing falls at the gym. I know the formula is something like X amount of feet per second per second. Can someone explain it to me and tell me how far a person falls the first second and third seconds?does it double each second or is it multiplied? How long till terminal velocity?

Post by **Yasmeen** » Mon Feb 24, 2003 1:52 am

32 feet per second per second, which is 10 meters per second per second. According to this site, terminal velocity varies with object compactness and density. I don't know much about physics though.

Post by **Legion** » Mon Feb 24, 2003 1:52 am

You've got it.
Acceleration (due to gravity) = 9.8 m/s/s
Velocity = acceleration * time

first second = 9.8 m/s, second second = 19.6 m/s, third second = 29.4 m/s

every second you are traveling 9.8 m/s faster

this doesn't factor in any kind of resistance...

if you want to figure out how fast you are going after falling a certain distance then use this:

velocity = SqrRoot(2*acceleration*distance)

so if you jumped off the top of el cap (~1000m) and there was no air resistance you would hit the ground at SqrRoot( 2 * 9.8m/s/s * 1000m ) = 140 m/s

which is about 313mph SPLAT!!!

don't know what terminal velocity is for a human. Somewhere around 140mph is sticking in my head. Anyone?

Post by **Yasmeen** » Mon Feb 24, 2003 2:08 am

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That link has the terminal velocity for skydivers

Post by **ynot** » Mon Feb 24, 2003 5:01 am

should be the same for climbers, yer link isnt showing.

Post by **Legion** » Mon Feb 24, 2003 5:28 am

About 125 mph for a flailing body, but around 200mph if you streamline yourself.

Post by **tomdarch** » Mon Feb 24, 2003 6:40 am

Legion wrote:About 125 mph for a flailing body, but around 200mph if you streamline yourself.

Wouldn't it depend on wether you're wearing those flappy-flappy skydiving outfits? (flapping=resistance)

Normal climbers would be wearing shorts and a t-shirt, thus less resistance, and a higher terminal velocity. Ironically, boulderers, with their caps and baggy pants, would likely end up slightly less dead if they fell off el cap!

Post by **Yasmeen** » Mon Feb 24, 2003 11:17 am

Yeah, and maybe even 202-203 if you were wearing aerodynamic lycra!

Post by **Rain Man** » Mon Feb 24, 2003 1:18 pm

As Legion noted, the 313 Mph vacume velocity applies for ANY falling body, feather, brick or body. Outside, though, a falling body's terminal velocity DOES depend on it's dimensions and shape (for determining the force of air friction and) and mass/weight ratio (density). For example, all things being equal, if ynot and I both lept off the top of El Cap at the same time I would land first and create a damping system for him to land on, absorbing some of his energy before the near instantaneous negative acceleration. The force (F=ma) of a falling body is the other major determining factor of terminal velocity (first being air friction based on the body's coefficient of drag). As Legion also noted, the more dense an object is, the higher its max vel. will be when it reaches equilibrium, so if ynot started pumping iron and gained 75 lbs and we both weight the same and jumped, he would be MY shock absorber...so, go ahead and start that program there, ok.

Post by **Legion** » Mon Feb 24, 2003 1:31 pm

How about if I rode a circus elephant with really big ears off the top of el cap?