Does the Weight of an Airplane and Contents Change?

The weight lost from perspiration and the passengers burning calories is
insignificant. Consider that a plane burns a few thousand pounds of fuel
per hour, then even if you had each person managing to burn a pound of
energy sustaining themselves on the flight (a generous guesstimate) on a
747 you'd come in ~400 lbs less at landing than takeoff. No biggie.

And that would assume the pound used to sustain themselves left the
plane. After all, if you lose a pound, it doesn't disappear, it goes
someplace.

Is excrement not jettisoned overboard? We have all heard stories of frozen
turds crashing through roofs.

freeda wrote:
Is excrement not jettisoned overboard? We have all heard stories of
frozen
turds crashing through roofs.


This might happen due to leakage, but this stuff is actually supposed to
stay in the tank until it is deposed of after landing.

"A Mate" wrote in message u...
"nobody" wrote in message
...
Alan Bell wrote:
after we eat, the same as when the plane took off? And what about two
hours
after we eat? When nature takes it course, is the aggregate weight still
the
same?

Overall, you sweat or exhale a lot of the water contents of the food you
eat/drink, and that humidity is dumped overboard as the air is replaced in
the cabin.

The E = MC2 aspect would probably be so small that it wouldn't matter with
regards to mass converted to energy by muscles.

E=mc2 - refers to energy creation and destruction of matter - as in a
nuclear or thermo-nuclear reaction. Nothing to do with the energy
transformations which occur in the human body!!

Slow down jasper. If we're picking nits, this ain't true. Energy
has mass. When energy is transferred, mass is transfered. When my
body expels heat, by conduction, convection, or radiation, it is
expelling mass. Now, the nit aspect is that the mass expelled is
incredibly tiny. Take the amount of energy radiated, divide by the
SQUARE of the speed of light and that's the amount of mass. I'm not
sure my calculator will display that many zeros. So if I have a window
seat, and I'm radiating heat out the window (a trick in and of itself
since the windows aren't transparent to most of the wavelengths I radiate)
mass is being lost. If I wind my watch, the spring in the watch gets
heavier. Truth is, when the aircraft takes off, and therefore accelerates
all of our bodies to higher kinetic energy states, it increases all of
our masses. So really, in the net sense, it isn't clear what "initial"
mass the original question is refering. It's probably safe to presume
"rest mass" though.


The aircraft would weigh exactly what it did on take-off MINUS the weight of
water lost in air exchange, fuel burnt and waste matter jettisoned through
the toilet and waste water systems.

Yes, this is the simple answer. If there is no mass exchange over
the fuselage boundary, the total mass will stay constant. So if
no air is being exchanged, and no fluids are being dumped, the total
mass has to stay constant.

after we eat, the same as when the plane took off? And what about
two
hours
after we eat? When nature takes it course, is the aggregate weight
still
the
same?

Overall, you sweat or exhale a lot of the water contents of the food
you
eat/drink, and that humidity is dumped overboard as the air is
replaced in
the cabin.

The E = MC2 aspect would probably be so small that it wouldn't matter
with
regards to mass converted to energy by muscles.

E=mc2 - refers to energy creation and destruction of matter - as in a
nuclear or thermo-nuclear reaction. Nothing to do with the energy
transformations which occur in the human body!!

Slow down jasper. If we're picking nits, this ain't true. Energy
has mass. When energy is transferred, mass is transfered. When my
body expels heat, by conduction, convection, or radiation, it is
expelling mass. Now, the nit aspect is that the mass expelled is
incredibly tiny. Take the amount of energy radiated, divide by the
SQUARE of the speed of light and that's the amount of mass. I'm not
sure my calculator will display that many zeros. So if I have a window
seat, and I'm radiating heat out the window (a trick in and of itself
since the windows aren't transparent to most of the wavelengths I radiate)
mass is being lost. If I wind my watch, the spring in the watch gets
heavier. Truth is, when the aircraft takes off, and therefore accelerates
all of our bodies to higher kinetic energy states, it increases all of
our masses. So really, in the net sense, it isn't clear what "initial"
mass the original question is refering. It's probably safe to presume
"rest mass" though.

Not quite true, the energy created by your body is a chemical reaction, not
a nuclear reaction. All that is changing is the bonds between molecules. ie
an exothermic reaction. (****, I really can't remember most of my scholo
chemistry).
Although what you are saying about an aircraft increasing in mass during
flight is true, your explanation is wrong, it has nothing to do with kinetic
energy. just do a google search for 'lorentz transformations', although the
amount will be negligable until you start approaching the speed of light.

"freeda" wrote in message
...
after we eat, the same as when the plane took off? And what about
two
hours
after we eat? When nature takes it course, is the aggregate weight
still
the
same?

Overall, you sweat or exhale a lot of the water contents of the food
you
eat/drink, and that humidity is dumped overboard as the air is
replaced in
the cabin.

The E = MC2 aspect would probably be so small that it wouldn't
matter
with
regards to mass converted to energy by muscles.

E=mc2 - refers to energy creation and destruction of matter - as in a
nuclear or thermo-nuclear reaction. Nothing to do with the energy
transformations which occur in the human body!!

Slow down jasper. If we're picking nits, this ain't true. Energy
has mass. When energy is transferred, mass is transfered. When my
body expels heat, by conduction, convection, or radiation, it is
expelling mass. Now, the nit aspect is that the mass expelled is
incredibly tiny. Take the amount of energy radiated, divide by the
SQUARE of the speed of light and that's the amount of mass. I'm not
sure my calculator will display that many zeros. So if I have a window
seat, and I'm radiating heat out the window (a trick in and of itself
since the windows aren't transparent to most of the wavelengths I
radiate)
mass is being lost. If I wind my watch, the spring in the watch gets
heavier. Truth is, when the aircraft takes off, and therefore
accelerates
all of our bodies to higher kinetic energy states, it increases all of
our masses. So really, in the net sense, it isn't clear what "initial"
mass the original question is refering. It's probably safe to presume
"rest mass" though.

Not quite true, the energy created by your body is a chemical reaction,
not
a nuclear reaction. All that is changing is the bonds between molecules.
ie
an exothermic reaction. (****, I really can't remember most of my scholo
chemistry).
Although what you are saying about an aircraft increasing in mass during
flight is true, your explanation is wrong, it has nothing to do with
kinetic
energy. just do a google search for 'lorentz transformations', although
the
amount will be negligable until you start approaching the speed of light.



Are you talking about relativistic mass or invarient mass ?

(and what is weight anyway) - If it is what is measured by a set of (very
large) bathroom scales it will also reduce as the aircraft moves further
away from the planet. So it will reduce during flight and increase again as
it comes back to land. (due to gravitational attraction)

after we eat, the same as when the plane took off? And what
about
two
hours
after we eat? When nature takes it course, is the aggregate
weight
still
the
same?

Overall, you sweat or exhale a lot of the water contents of the
food
you
eat/drink, and that humidity is dumped overboard as the air is
replaced in
the cabin.

The E = MC2 aspect would probably be so small that it wouldn't
matter
with
regards to mass converted to energy by muscles.

E=mc2 - refers to energy creation and destruction of matter - as in
a
nuclear or thermo-nuclear reaction. Nothing to do with the energy
transformations which occur in the human body!!

Slow down jasper. If we're picking nits, this ain't true. Energy
has mass. When energy is transferred, mass is transfered. When my
body expels heat, by conduction, convection, or radiation, it is
expelling mass. Now, the nit aspect is that the mass expelled is
incredibly tiny. Take the amount of energy radiated, divide by the
SQUARE of the speed of light and that's the amount of mass. I'm not
sure my calculator will display that many zeros. So if I have a
window
seat, and I'm radiating heat out the window (a trick in and of itself
since the windows aren't transparent to most of the wavelengths I
radiate)
mass is being lost. If I wind my watch, the spring in the watch gets
heavier. Truth is, when the aircraft takes off, and therefore
accelerates
all of our bodies to higher kinetic energy states, it increases all of
our masses. So really, in the net sense, it isn't clear what
"initial"
mass the original question is refering. It's probably safe to presume
"rest mass" though.

Not quite true, the energy created by your body is a chemical reaction,
not
a nuclear reaction. All that is changing is the bonds between molecules.
ie
an exothermic reaction. (****, I really can't remember most of my scholo
chemistry).
Although what you are saying about an aircraft increasing in mass during
flight is true, your explanation is wrong, it has nothing to do with
kinetic
energy. just do a google search for 'lorentz transformations', although
the
amount will be negligable until you start approaching the speed of
light.



Are you talking about relativistic mass or invarient mass ?

(and what is weight anyway) - If it is what is measured by a set of (very
large) bathroom scales it will also reduce as the aircraft moves further
away from the planet. So it will reduce during flight and increase again
as
it comes back to land. (due to gravitational attraction)


Mass then. and talking about relativistic mass.

Not quite true, the energy created by your body is a chemical
reaction,
not
a nuclear reaction. All that is changing is the bonds between
molecules.
ie
an exothermic reaction. (****, I really can't remember most of my
scholo
chemistry).
Although what you are saying about an aircraft increasing in mass
during
flight is true, your explanation is wrong, it has nothing to do with
kinetic
energy. just do a google search for 'lorentz transformations',
although
the
amount will be negligable until you start approaching the speed of
light.



Are you talking about relativistic mass or invarient mass ?

(and what is weight anyway) - If it is what is measured by a set of
(very
large) bathroom scales it will also reduce as the aircraft moves further
away from the planet. So it will reduce during flight and increase again
as
it comes back to land. (due to gravitational attraction)


Mass then. and talking about relativistic mass.


Which most scientists would argue is a little irrelevant :-)

But going back to an offshoot from the OP's original question, how much the
weight of the aircraft be reduced at 30,000 feet due to the reduction in
gravity ?

(Assuming the positions of the moon and sun can be discounted).

mtravelkay wrote:
ender wrote:


The weight lost from perspiration and the passengers burning calories
is insignificant. Consider that a plane burns a few thousand pounds of
fuel per hour, then even if you had each person managing to burn a
pound of energy sustaining themselves on the flight (a generous
guesstimate) on a 747 you'd come in ~400 lbs less at landing than
takeoff. No biggie.


And that would assume the pound used to sustain themselves left the
plane. After all, if you lose a pound, it doesn't disappear, it goes
someplace.


I'm not talking about people ****ting here. When you sit at your
computer, your body burns calories generating heat, speaking, moving
around, digesting food, etc. The mass of food you ate on the plane or
before boarding is converted to heat, sound, kinetic energy. The fact
that people sit on a plane more or less emphasizes that this loss of
energy, and the mass used to create it, is tiny, and therefore negligible.

"Miss L. Toe" wrote in message
...

But going back to an offshoot from the OP's original question, how much
the
weight of the aircraft be reduced at 30,000 feet due to the reduction in
gravity ?

(Assuming the positions of the moon and sun can be discounted).

Gravity goes as the inverse square of the distance.
Taking the initial distance, r0, to be at the surface
of the Earth where the weight of the plane is w0:

r0 = 6380 km (approximately)

w1/w0 = (r0/r1)^2

=(r0/(r0 + h))^2 h is the plane's height above r0

30,000 feet is about 9.14 km. So the weight ratio becomes:

w1/w0 = (6380/(6380 + 9.14))^2

= 0.997

The weight change is about 0.3% .

On Tue, 23 Mar 2004 15:36:43 -0000, "Miss L. Toe"
wrote:


Not quite true, the energy created by your body is a chemical
reaction,
not
a nuclear reaction. All that is changing is the bonds between
molecules.
ie
an exothermic reaction. (****, I really can't remember most of my
scholo
chemistry).
Although what you are saying about an aircraft increasing in mass
during
flight is true, your explanation is wrong, it has nothing to do with
kinetic
energy. just do a google search for 'lorentz transformations',
although
the
amount will be negligable until you start approaching the speed of
light.



Are you talking about relativistic mass or invarient mass ?

(and what is weight anyway) - If it is what is measured by a set of
(very
large) bathroom scales it will also reduce as the aircraft moves further
away from the planet. So it will reduce during flight and increase again
as
it comes back to land. (due to gravitational attraction)


Mass then. and talking about relativistic mass.


Which most scientists would argue is a little irrelevant :-)

But going back to an offshoot from the OP's original question, how much the
weight of the aircraft be reduced at 30,000 feet due to the reduction in
gravity ?

(Assuming the positions of the moon and sun can be discounted).

No change, as the ambiguous word "weight" is normally used in the
context of aircraft loading.

But for the different definition of weight which you obviously have in
mind, 30 000 ft above where? Note that 30 000 ft above the North Pole
is 60 000 ft closer to the center of Earth than the surface at the top
of Mt. Chimborazo, and 30 000 ft above Mt. Chimborazo is 20 970 000 ft
farther from the axis of rotation than the surface at the North Pole.

Gene Nygaard
http://ourworld.compuserve.com/homepages/Gene_Nygaard/