 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
According to the textbooks, it takes 1 Jule to move a 1 kg object a
distance of 1 meter.
On the other hand, once the object has been moved, keeping it stationary
requires no energy at all. And, indeed, if you take a lump of metal and
put it on your bookshelf, it requires no energy to make it remain there.
It just sits there like a lifeless lump of metal.
Now, here's the thing: How much energy does it take to hold a 1 kg lump
of metal at arm's legnth?
According to physics, it would require 0 Jules. However, to keep the
object stationary against the force of gravity, the muscles in your arm
are having to continually expend chemical energy. But how the **** do
you compute how much energy that is??
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 31/07/2010 3:21 PM, Orchid XP v8 wrote:
> According to physics, it would require 0 Jules. However, to keep the
> object stationary against the force of gravity, the muscles in your arm
> are having to continually expend chemical energy. But how the **** do
> you compute how much energy that is??
Analyse the system and come back with an answer. This is 3rd year high
school mechanics.
--
Best Regards,
Stephen
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Stephen wrote:
> Analyse the system and come back with an answer. This is 3rd year high
> school mechanics.
Riiiight. Too bad I didn't do that class, eh?
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 31/07/2010 3:54 PM, Orchid XP v8 wrote:
> Stephen wrote:
>
>> Analyse the system and come back with an answer. This is 3rd year high
>> school mechanics.
>
> Riiiight. Too bad I didn't do that class, eh?
>
Well use your big brain and work it out from first principles
--
Best Regards,
Stephen
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Le 31/07/2010 16:21, Orchid XP v8 nous fit lire :
> According to the textbooks, it takes 1 Jule to move a 1 kg object a
> distance of 1 meter.
Objection. It (1 Joule) is the work of a Force of 1 Newton whose point
of application is moving by a distance of 1 meter along the direction of
the force.
1 kg is a mass, not a force. Your planet might influence the number of
Joule to move such a mass.
1 Joule is also the energy transformed in heat in 1 second by a 1 Ohm
resistor when the current is 1 ampere.
>
> On the other hand, once the object has been moved, keeping it stationary
> requires no energy at all. And, indeed, if you take a lump of metal and
> put it on your bookshelf, it requires no energy to make it remain there.
> It just sits there like a lifeless lump of metal.
>
> Now, here's the thing: How much energy does it take to hold a 1 kg lump
> of metal at arm's legnth?
>
> According to physics, it would require 0 Jules. However, to keep the
> object stationary against the force of gravity, the muscles in your arm
> are having to continually expend chemical energy. But how the **** do
> you compute how much energy that is??
>
According to physic, the global work is null.
What are the forces:
- gravity, F= 1*g Newton (g ~ 9.81 ?) for the lump of metal, vertical,
downward
- gravity on your arm, vertical, downward
- muscles on the shoulder, vertical, upward when converted from couple.
What is the weight of your arm ?
What is its length ? (we have a couple to nullify to reach static)
(we assume so far the other joints of the arms are locked by the bones &
position, it might be different and might introduce more forces)
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Le_Forgeron <jgr### [at] free fr> wrote:
> According to physic, the global work is null.
At least according to newtonian physics. I'm wondering if general
relativity muddles this because it says (and there's rather compelling
empirical evidence that GR is right in this) that the object sitting on
the shelf is actually in a constant state of acceleration (while, perhaps
rather ironically, a free-falling object is not, which is kind of the
complete reverse of what newtonian mechanics says).
It's curious, even though I have read quite some material about both
newtonian mechanics and both theories of relativity, it's still unclear
to me how the "traditional" postulates of newtonian mechanics (such as
the quintessential "F=ma" and other such basic formulas) work when we
take general relativity into account (especially when we are talking
about gravity rather than simply forces applied to objects floating
in zero gravity).
In classical newtonian mechanics the total amount of work performed
on an object on the floor is zero, but is it also in general relativity?
How does GR affect this? Or does it affect at all?
--
- Warp
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
>> According to the textbooks, it takes 1 Jule to move a 1 kg object a
>> distance of 1 meter.
>
> Objection. It (1 Joule) is the work of a Force of 1 Newton whose point
> of application is moving by a distance of 1 meter along the direction of
> the force.
>
> 1 kg is a mass, not a force. Your planet might influence the number of
> Joule to move such a mass.
Yeah. It _is_ kind of conspicuous that all the examples talk about
*lifting* an object. As if moving an object horizontally wouldn't
require any energy or something...
> 1 Joule is also the energy transformed in heat in 1 second by a 1 Ohm
> resistor when the current is 1 ampere.
And here I was thinking that the heat produced depends on the
characteristics of the material, not just the current...
>> Now, here's the thing: How much energy does it take to hold a 1 kg lump
>> of metal at arm's legnth?
>>
> According to physic, the global work is null.
> What are the forces:
> - gravity, F= 1*g Newton (g ~ 9.81 ?) for the lump of metal, vertical,
> downward
> - gravity on your arm, vertical, downward
> - muscles on the shoulder, vertical, upward when converted from couple.
>
> What is the weight of your arm ?
> What is its length ? (we have a couple to nullify to reach static)
> (we assume so far the other joints of the arms are locked by the bones &
> position, it might be different and might introduce more forces)
Mmm, interesting.
I guess ultimately, muscles generate forces. Presumably to hold an
object still, the force generated by the total muscle system must be
equal (and opposite to) the force of gravity. It's all quite
complicated, since most forms of locomation involve levering, and you'd
have to know muscle insertion points and pivot lengths and so on.
I guess the really interesting question is, how much energy does it take
for a muscle to produce a given amount of force? (And, perhaps more
importantly, what variables does this depend on?)
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On 31/07/2010 9:36 PM, Orchid XP v8 wrote:
> Yeah. It _is_ kind of conspicuous that all the examples talk about
> *lifting* an object. As if moving an object horizontally wouldn't
> require any energy or something...
>
That is because it is the simplest to describe. When you master this we
will move on to friction on a horizontal plane then an inclined plane.
>> 1 Joule is also the energy transformed in heat in 1 second by a 1 Ohm
>> resistor when the current is 1 ampere.
>
> And here I was thinking that the heat produced depends on the
> characteristics of the material, not just the current...
>
The characteristics of the material is reflected in the resistance or
vica versa.
>> What is the weight of your arm ?
>> What is its length ? (we have a couple to nullify to reach static)
>> (we assume so far the other joints of the arms are locked by the bones &
>> position, it might be different and might introduce more forces)
>
> Mmm, interesting.
>
> I guess ultimately, muscles generate forces. Presumably to hold an
> object still, the force generated by the total muscle system must be
> equal (and opposite to) the force of gravity. It's all quite
> complicated, since most forms of locomation involve levering, and you'd
> have to know muscle insertion points and pivot lengths and so on.
>
> I guess the really interesting question is, how much energy does it take
> for a muscle to produce a given amount of force? (And, perhaps more
> importantly, what variables does this depend on?)
>
You are getting there :-D
--
Best Regards,
Stephen
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Stephen" <mca### [at] aolDOTcom> wrote in message
news:4c54356b@news.povray.org...
> On 31/07/2010 3:21 PM, Orchid XP v8 wrote:
> > According to physics, it would require 0 Jules. However, to keep the
> > object stationary against the force of gravity, the muscles in your arm
> > are having to continually expend chemical energy. But how the **** do
> > you compute how much energy that is??
> Analyse the system and come back with an answer. This is 3rd year high
> school mechanics.
The question has almost nothing to do with mechanics *or* high school. It's
biological/physiological and dependant on many complex factors. You almost
never compute such things by "analysing the system" and working from basic
principles, but you make empirical measurements.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Orchid XP v8 wrote:
> Yeah. It _is_ kind of conspicuous that all the examples talk about
> *lifting* an object. As if moving an object horizontally wouldn't
> require any energy or something...
It doesn't, in the physics definition of "energy". Other than the fact that
you expend energy to accelerate the object and more energy to decelerate it,
and to overcome friction and such. But if it's (say) sitting on a
frictionless surface, you can move it as far as you want with as little
energy as you want.
You're thinking the physics definition of "energy" has something to do with
"effort". The physics definition of "energy" has to do with how much work
you can make the mass under consideration perform. I.e., if it's the weight
on a pendulum clock, and the clock is stopped because you're holding it up,
you're neither making the clock capable of running longer nor shorter
because you're holding it.
--
Darren New, San Diego CA, USA (PST)
C# - a language whose greatest drawback
is that its best implementation comes
from a company that doesn't hate Microsoft.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Warp wrote:
> How does GR affect this? Or does it affect at all?
I believe that at least for this case, the energy change shows up as a
change in "m". In other words, "F=ma" still holds, but you use E=mc^2 to
calculate the actual mass. (At least in special relativity, that's how you
work it.)
--
Darren New, San Diego CA, USA (PST)
C# - a language whose greatest drawback
is that its best implementation comes
from a company that doesn't hate Microsoft.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Orchid XP v8 wrote:
> According to the textbooks, it takes 1 Jule to move a 1 kg object a
> distance of 1 meter.
If one Newton force is applied in the direction of motion for the whole
distance, yes.
> On the other hand, once the object has been moved, keeping it stationary
> requires no energy at all. And, indeed, if you take a lump of metal and
> put it on your bookshelf, it requires no energy to make it remain there.
> It just sits there like a lifeless lump of metal.
Quite true.
> Now, here's the thing: How much energy does it take to hold a 1 kg lump
> of metal at arm's legnth?
>
> According to physics, it would require 0 Jules.
If this were true, then it would take no effort to do this. You concept
of this being "according to physics" is off a bit.
> However, to keep the
> object stationary against the force of gravity, the muscles in your arm
> are having to continually expend chemical energy.
This is because the 1kg object is resting on a system of tensed muscles,
instead of a rigid framework. The tense muscles expend energy in order
to maintain their tension.
> But how the **** do you compute how much energy that is??
Exercise physiologists would probably measure the oxygen consumption of
a person at rest vs. a person holding the weight at arm's length. The
difference corresponds to the extra requirements.
Regards,
John
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Am 31.07.2010 16:21, schrieb Orchid XP v8:
> According to physics, it would require 0 Jules. However, to keep the
> object stationary against the force of gravity, the muscles in your arm
> are having to continually expend chemical energy. But how the **** do
> you compute how much energy that is??
Measure the amount of Co2 you exhale (a) normally, and (b) while
performing said feat, then from the difference compute the extra Co2
produced for that feat, and from that estimate the energy?
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Am 31.07.2010 16:38, schrieb Stephen:
>> According to physics, it would require 0 Jules. However, to keep the
>> object stationary against the force of gravity, the muscles in your arm
>> are having to continually expend chemical energy. But how the **** do
>> you compute how much energy that is??
>
> Analyse the system and come back with an answer. This is 3rd year high
> school mechanics.
... plus university level biochemistry, yes.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Am 31.07.2010 22:36, schrieb Orchid XP v8:
>> 1 Joule is also the energy transformed in heat in 1 second by a 1 Ohm
>> resistor when the current is 1 ampere.
>
> And here I was thinking that the heat produced depends on the
> characteristics of the material, not just the current...
In a sense that's true - but the material characteristics influence the
resistance /exactly/ the same way as the heat produced ;-)
> I guess ultimately, muscles generate forces. Presumably to hold an
> object still, the force generated by the total muscle system must be
> equal (and opposite to) the force of gravity. It's all quite
> complicated, since most forms of locomation involve levering, and you'd
> have to know muscle insertion points and pivot lengths and so on.
The thing with muscles is, they never actually hold something still
unless they're totally slack. When they're contracted, they actually
twitch at a high frequency, thus repetitively lifting the weight up a
bit, converting chemical energy to potential energy, then letting the
weight drop a bit only to catch it again a split second later, wasting
some of the energy as heat. (The tendons help "recycling" some of the
kinetic energy by converting it into mechanical energy like a spring,
and kangaroos make pretty effective use of this mechanism for moving
around, but even they lose part of the energy as heat, thus effecting
global warming and ultimately the entropy death of the universe... but
maybe I'm drifting off here :-).)
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
>> According to physics, it would require 0 Jules. However, to keep the
>> object stationary against the force of gravity, the muscles in your arm
>> are having to continually expend chemical energy. But how the **** do
>> you compute how much energy that is??
>
> Measure the amount of Co2 you exhale (a) normally, and (b) while
> performing said feat, then from the difference compute the extra Co2
> produced for that feat, and from that estimate the energy?
Sure. Now tell me how much energy is released by the production of 1
unit of CO2...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
>>> 1 Joule is also the energy transformed in heat in 1 second by a 1 Ohm
>>> resistor when the current is 1 ampere.
>>
>> And here I was thinking that the heat produced depends on the
>> characteristics of the material, not just the current...
>
> In a sense that's true - but the material characteristics influence the
> resistance /exactly/ the same way as the heat produced ;-)
Hmm, interesting.
> The thing with muscles is, they never actually hold something still
> unless they're totally slack. When they're contracted, they actually
> twitch at a high frequency
Individual fibers twitch, yes. A single "muscle" contains rather a lot
of individual fibers though, all twitching in a coordinated pattern. The
net result is more or less contant tension.
I'm told this is why when you try to lift something too heavy, you start
shaking. You run out of fibers to twitch.
(Related... I'm told that if *all* the fibers were to twitch at once,
the muscle would probably tear itself from its attachment points. Which
perhaps explains why people undergoing convulsions sometimes display
superhuman strength.)
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Am 01.08.2010 18:16, schrieb Orchid XP v8:
>> The thing with muscles is, they never actually hold something still
>> unless they're totally slack. When they're contracted, they actually
>> twitch at a high frequency
>
> Individual fibers twitch, yes. A single "muscle" contains rather a lot
> of individual fibers though, all twitching in a coordinated pattern. The
> net result is more or less contant tension.
>
> I'm told this is why when you try to lift something too heavy, you start
> shaking. You run out of fibers to twitch.
>
> (Related... I'm told that if *all* the fibers were to twitch at once,
> the muscle would probably tear itself from its attachment points. Which
> perhaps explains why people undergoing convulsions sometimes display
> superhuman strength.)
Hm, I didn't know /that/ (and I'm still doubtful about it). Still, the
result is only "more or less constant" tension, so there /is/ some
inevitable net twitching.
If it's true though, then the energy you burn to hold something steady
is actually the energy you need to overcome the friction in your muscles.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Am 01.08.2010 18:12, schrieb Orchid XP v8:
>>> According to physics, it would require 0 Jules. However, to keep the
>>> object stationary against the force of gravity, the muscles in your arm
>>> are having to continually expend chemical energy. But how the **** do
>>> you compute how much energy that is??
>>
>> Measure the amount of Co2 you exhale (a) normally, and (b) while
>> performing said feat, then from the difference compute the extra Co2
>> produced for that feat, and from that estimate the energy?
>
> Sure. Now tell me how much energy is released by the production of 1
> unit of CO2...
I guess some biochemistry experts have already done elaborate studies on
this subject, so it's just a matter of finding the right paper to give
you this answer.
For instance, you could do the same measurements on a person working out
on an ergometer (a high-quality "calibrated" treadmill, stationary
bicycle or similar device) at different loads.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
clipka wrote:
> I guess some biochemistry experts have already done elaborate studies on
> this subject, so it's just a matter of finding the right paper to give
> you this answer.
Oooo! Ooooo! I know that one!
http://en.wikipedia.org/wiki/Citric_acid_cycle
--
Darren New, San Diego CA, USA (PST)
C# - a language whose greatest drawback
is that its best implementation comes
from a company that doesn't hate Microsoft.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Orchid XP v8" <voi### [at] devnull> a écrit dans le message de groupe de
discussion : 4c559d0e$1@news.povray.org...
> Sure. Now tell me how much energy is released by the production of 1 unit
> of CO2...
These kind of measurements are made in special boxes named metabolic
chambers. I've seen some made for pigs and cows but here's one for people
(with a real bed and all) :
http://labs.pbrc.edu/energymetabolism/MetabolicChambers.htm
G.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
And lo On Sat, 31 Jul 2010 15:21:31 +0100, Orchid XP v8 <voi### [at] devnull>
did spake thusly:
> According to the textbooks, it takes 1 Jule to move a 1 kg object a
> distance of 1 meter.
>
> On the other hand, once the object has been moved, keeping it stationary
> requires no energy at all. And, indeed, if you take a lump of metal and
> put it on your bookshelf, it requires no energy to make it remain there.
> It just sits there like a lifeless lump of metal.
>
> Now, here's the thing: How much energy does it take to hold a 1 kg lump
> of metal at arm's legnth?
>
> According to physics, it would require 0 Jules. However, to keep the
> object stationary against the force of gravity, the muscles in your arm
> are having to continually expend chemical energy. But how the **** do
> you compute how much energy that is??
To ask it another way how much energy is the bookshelf using to keep the
lump of metal from falling through it under the influence of gravity ;-)
--
Phil Cook
--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Phil Cook v2 wrote:
> To ask it another way how much energy is the bookshelf using to keep the
> lump of metal from falling through it under the influence of gravity ;-)
That's really not the right way to ask the question. The right way to ask
the question is how much more work can the lump of metal do after sitting on
the bookshelf (or in your hand) for 30 seconds? It hasn't anything to do
with how much effort it takes to hold it. It has to do with the final
resulting configuration.
--
Darren New, San Diego CA, USA (PST)
C# - a language whose greatest drawback
is that its best implementation comes
from a company that doesn't hate Microsoft.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
It's a simple question, but requires one to sharpen one's physics vocabulary
greatly in order to answer it.
First of all, the missing concept in your question is WORK. There is zero work
required if one were to hold an object stationary against a force. Work is
force times distance. If you lift an object, you do the work of force x distance
and increase its gravitational potential energy. Again, holding it stationary
is zero work.
It may be ironic that it still takes "effort" on your muscles' part to hold it
still, even if they do no work. Perhaps it helps to think of how athletes engage
in weightLIFTING, not weightHOLDING. There's more exercise in the WORK.
Just typing here: putting a 20 pound, expertly-designed backpack on my back
isn't as much "exercise" as is holding a 2 pound weight at arms length. And the
latter hurts your muscles more because of the fulcrum-- you've got to put a huge
force on one side of the fulcrum's short arm inside your body in order to
balance out the small force held out at the (literally) long "arm". In the case
where your arm shakes, you may do work up and down over and over, getting more
tired.
But will you burn more calories by holding that weight at arm's length? I'm
sure. I guess I've run out of my area of expertise to say anything more about
that.
Orchid XP v8 <voi### [at] devnull> wrote:
> According to the textbooks, it takes 1 Jule to move a 1 kg object a
> distance of 1 meter.
>
> On the other hand, once the object has been moved, keeping it stationary
> requires no energy at all. And, indeed, if you take a lump of metal and
> put it on your bookshelf, it requires no energy to make it remain there.
> It just sits there like a lifeless lump of metal.
>
> Now, here's the thing: How much energy does it take to hold a 1 kg lump
> of metal at arm's legnth?
>
> According to physics, it would require 0 Jules. However, to keep the
> object stationary against the force of gravity, the muscles in your arm
> are having to continually expend chemical energy. But how the **** do
> you compute how much energy that is??
>
> --
> http://blog.orphi.me.uk/
> http://www.zazzle.com/MathematicalOrchid*
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
clipka <ano### [at] anonymousorg> wrote:
> Am 31.07.2010 22:36, schrieb Orchid XP v8:
>
> >> 1 Joule is also the energy transformed in heat in 1 second by a 1 Ohm
> >> resistor when the current is 1 ampere.
> >
> > And here I was thinking that the heat produced depends on the
> > characteristics of the material, not just the current...
>
> In a sense that's true - but the material characteristics influence the
> resistance /exactly/ the same way as the heat produced ;-)
>
Heat is heat is heat. If heat is generated, heat is generated. Don't confuse
that with _temperature_ . The temperature that objects rise to will depend on a
number of properties, starting with _heat_capacity_ and eventually influenced
by _thermal_conductivity_ , convection currents in the neighborhood, etc.. A 1
Ohm aluminum and 1 ohm tungsten wire will warm up differently, even if the same
heat were generated.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Am 02.08.2010 22:32, schrieb gregjohn:
> clipka<ano### [at] anonymousorg> wrote:
>> Am 31.07.2010 22:36, schrieb Orchid XP v8:
>>
>>>> 1 Joule is also the energy transformed in heat in 1 second by a 1 Ohm
>>>> resistor when the current is 1 ampere.
>>>
>>> And here I was thinking that the heat produced depends on the
>>> characteristics of the material, not just the current...
>>
>> In a sense that's true - but the material characteristics influence the
>> resistance /exactly/ the same way as the heat produced ;-)
>>
>
>
> Heat is heat is heat. If heat is generated, heat is generated. Don't confuse
> that with _temperature_ . The temperature that objects rise to will depend on a
> number of properties, starting with _heat_capacity_ and eventually influenced
> by _thermal_conductivity_ , convection currents in the neighborhood, etc.. A 1
> Ohm aluminum and 1 ohm tungsten wire will warm up differently, even if the same
> heat were generated.
Don't worry, I'm not confusing these things here. I guess Andy has
gotten the point I intended to make: "Sure, there are experimental
setups where the heat generated by a sample resistor at a given current
depends on the material characteristics - but you're forgetting that
those experiments don't have a constant resistance either."
Not really contradicting what you say, is it?
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Am 02.08.2010 18:22, schrieb gregjohn:
> I guess I've run out of my area of expertise to say anything more about
> that.
Duh - since when does one have to have /expertise/ to contribute to a
topic here? :-P
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> According to physics, it would require 0 Jules. However, to keep the
> object stationary against the force of gravity, the muscles in your arm
> are having to continually expend chemical energy. But how the **** do you
> compute how much energy that is??
If your heart rate monitor shows calories burned then just use this (with
and without the object), should give a rough approximation.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
scott wrote:
>> According to physics, it would require 0 Jules. However, to keep the
>> object stationary against the force of gravity, the muscles in your
>> arm are having to continually expend chemical energy. But how the ****
>> do you compute how much energy that is??
>
> If your heart rate monitor shows calories burned then just use this
> (with and without the object), should give a rough approximation.
And then you have to wonder, how the hell can the heart monitor
determine how many calories you're burning just from your heart rate?
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> And then you have to wonder, how the hell can the heart monitor determine
> how many calories you're burning just from your heart rate?
Presumably it just has some kind of lookup table or formula based on heart
rate, age and weight (assuming you entered those values, I had to on mine),
taken from actual experiments on humans.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
scott wrote:
>> And then you have to wonder, how the hell can the heart monitor
>> determine how many calories you're burning just from your heart rate?
>
> Presumably it just has some kind of lookup table or formula based on
> heart rate, age and weight (assuming you entered those values, I had to
> on mine), taken from actual experiments on humans.
I don't think mine has that data. Presumably it's just estimating based
on the population average or something then. It strikes me that even
with fairly accurate physical data, it would be a fairly vague estimate.
That reminds me - I need to go read the manual to find out how the hell
to turn off the beeping...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|
