how does the weight of a human

[AVAFREAK182]

???

 

[BlackTigers]

Read the chapter in your 10th grade physics book, then try again.

 

[FleshLight]

F = ma

 

[eLiu]

It does in the sense that a fatass will have more surface area than a skinny person (so more drag). But the effect should be pretty small.

 

[KillerCharlie]

Originally posted by: eLiu
It does in the sense that a fatass will have more surface area than a skinny person (so more drag). But the effect should be pretty small.

For the same shape (and size), a heavier object will reach a higher terminal velocity.

 

[dighn]

air resistance is a function of air speed. at steady state (down force = resistance), a heavier object requires a higher air resistance so that translates into a higher speed. a heavier person probably is larger, so that means more resistance at the same speed, but the two factors most likely don't cancel each other out exactly so the final speed is changed.

 

[TraumaRN]

There is a huge difference between streamline vertically down and spread eagle horizontal when sky diving...

Skydivers reach terminal velocity (around 120 mph (190 km/h) for belly to Earth(aka horizontal/spread eagle) orientations, 150-200 mph (240-320 km/h) for head down(aka vertical streamline) orientations

 

[IronWing]

Experimentation is the basis for all science. Throw a selection of children off a tall building and clock their descents. Be sure to weigh them before hand.

 

[flxnimprtmscl]

Originally posted by: ironwing
Experimentation is the basis for all science. Throw a selection of children off a tall building and clock their descents. Be sure to weigh them before hand.

I hate children so I definitely like this idea.

 

[sandorski]

Galileo would smack you.

 

[IronWing]

Originally posted by: sandorski
Galileo would smack you.

Screw that old infidel.

 

[Duddy]

F=ma, Newton's Second Law.

EDIT: FleshLight got it first.

 

[yhelothar]

Originally posted by: KillerCharlie

Originally posted by: eLiu
It does in the sense that a fatass will have more surface area than a skinny person (so more drag). But the effect should be pretty small.

For the same shape (and size), a heavier object will reach a higher terminal velocity.

In other words, higher density = higher terminal velocity

 

[George P Burdell]

Terminal velocity is directly proportional to square root of mass.

 

[Nik]

vM?

lol it took me like 10 minutes to find that damn square root symbol in the character map

 

[irishScott]

v^2(final) - v^2(initial) = 2a * displacement (delta x)

In freefall a = g = 9.81 m/s^2

Figure it out. Then figure out air resistance, which depends on numerous other factors, subtract the 2 and you've got it. I don't have the formula for air resistance memorized.

 

[theeedude]

Well, it's proportional to sqrt(m/A)
m is proportional to cube of height, A (cross sectional area) is proportional to square.

So terminal velocity is proportional to sqrt (m/(m^(2/3))) = sqrt(m^(1/3)) = m^(1/6), so it is proportional to the 6th root of the mass.

 

[dighn]

Originally posted by: irishScott
v^2(final) - v^2(initial) = 2a * displacement (delta x)

In freefall a = g = 9.81 m/s^2

Figure it out. Then figure out air resistance, which depends on numerous other factors, subtract the 2 and you've got it. I don't have the formula for air resistance memorized.

that doesn't apply very well here

assuming friction is proportional to sqr of speed, that is, a*v^2 where a is a constant. gravitational pull = mg, then at steady state speed is constant so acceleration = 0 => net force = 0 => friction = weight => v = sqrt(g/a)* sqrt(m) => proportional to sqrt(m) assuming the original a is relatively unchanged (e.g. same shape size etc)

 

[George P Burdell]

Before anyone else butchers high school physics facepalm; ), here is the entire formula:

V = v( (2mg) / (?Ak) )

where
V = terminal velocity of object free-falling in air
m = mass
g = acceleration due to gravity
? = density of air
A = projected area
k = drag coefficient

 

[dighn]

Originally posted by: George P Burdell
Before anyone else butchers high school physics facepalm; ), here is the entire formula:

V = v( (2mg) / (?Ak) )

where
V = terminal velocity of object free-falling in air
m = mass
g = acceleration due to gravity
? = density of air
A = projected area
k = drag coefficient

giving him the final formula isn't the same as telling him WHY

 

[George P Burdell]

Originally posted by: dighn

Originally posted by: George P Burdell
Before anyone else butchers high school physics facepalm; ), here is the entire formula:

V = v( (2mg) / (?Ak) )

where
V = terminal velocity of object free-falling in air
m = mass
g = acceleration due to gravity
? = density of air
A = projected area
k = drag coefficient

giving him the final formula isn't the same as telling him WHY

Good point, let me look it up.

EDIT: OK Wikipedia has it. At terminal velocity, a free falling object is at equilibrium. Or,
mg = drag force.

But drag force = 0.5 ?Ak v² (yes, another formula, derivation available online)

Therefore,
mg = 0.5 ?Ak V²

Rearranging, we get
V = v( (2mg) / (?Ak) )

 

[RapidSnail]

Originally posted by: flxnimprtmscl

Originally posted by: ironwing
Experimentation is the basis for all science. Throw a selection of children off a tall building and clock their descents. Be sure to weigh them before hand.

I hate children so I definitely like this idea.

Then you start.

 

[DrPizza]

It's all about surface area.

Weight is directly proportional to volume. Given the same density, if you double the weight, you double the volume.
However, if you double the volume, you do NOT double the surface area.

For simplicity, let's look at a sphere and go about it backwards: formula for volume is 4/3 Pi r^3. Formula for SA is 4 Pi r²
If you double the radius, you'll have 8 times the volume, but only 4 times the surface area. A heavier sphere will fall faster through the air.

Now, the shape of a human is more complicated, but SA and volume scale up the same way. And lastly, just a prediction here, if you have a 150 pound lean man, and a 150 pound obese child, I think the man would fall faster as he would have a smaller volume (higher density), thus smaller SA. I doubt it would make that much of a difference though.

 

[FoBoT]

w0w, i see Nik!

 

[sdifox]

Originally posted by: Nik
vM?

lol it took me like 10 minutes to find that damn square root symbol in the character map

http://www.asciitable.com/