| Topic: |
Science > Physics |
| User: |
"Charlie Johnson" |
| Date: |
19 Aug 2006 09:27:12 AM |
| Object: |
Weight & mass question |
Hi all,
I am confused, as usual. Say I weigh 200 lbs. measured by a typical
bathroom scale. If I convert that to newtons, I get (4.45 N)(220 lbs.) =
890 newtons. Now, to find my mass, I divide 890 N / 9.8 m/s^2 to get 91 kg.
But, if I convert my 200 lbs. to kilograms by the coversion 2.2 lbs / kg, I
get 91 kg. How can my weight be the same as my mass, if weight is mass x
acceleration?
What am I doing wrong here? Please help the befuddled!
T.I.A.
Lurch
.
|
|
| User: "The Ghost In The Machine" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 01:00:41 PM |
|
|
In sci.physics, cnctut
<cnctutwiler@wmconnect.com>
wrote
on 20 Aug 2006 09:27:14 -0700
<1156091234.820969.198850@h48g2000cwc.googlegroups.com>:
Ben Newsam wrote:
On Sun, 20 Aug 2006 13:42:54 GMT, "Sorcerer"
<Headmaster@hogwarts.physics_a> wrote:
"cnctut" <cnctutwiler@wmconnect.com> wrote in message
news:1156050446.429728.261790@75g2000cwc.googlegroups.com...
| I'm sure we've come a long way since the old shoe store X-ray
| machines--and those X-ray glasses sold years ago on the back page of
| comics. ;-))
Egads... if you remember those then you are not so young anymore.
Still, it was fun wiggling green metatarsals and phalanges.
I remember them. They were banned because of being dangerous. I have
often wondered just how dangerous they were, my little tootsies were
shoved into one of those several times.
--
Posted via a free Usenet account from http://www.teranews.com
//
Ben,
I don't know how dangerous they were--my feet still look
normal--perhaps the risk was more for employees who work around the
machines. I did see one recently that was still being used at the foot
doctors office (when my wife broke her foot.) Not sure they had any
practical value for selling shoes, other than as a sales gimmic--but I
never sold shoes--so I don't know for sure. I would like to have one in
the garage for various projects I'll never get to.
If everything is as dangerous as some suggest--mercury, lead etc--I
should have been dead years ago. I experimented as a child with all
that stuff--vapors, touching, etc. Now one drop of mercury shutsdown a
school until HAZMAT cleans it up.
Can't be too careful; al Qaeda might use that drop to make a small
amount of mercury fulminate.
:-)
Best Wishes,
Tut
--
#191,
Windows Vista. Because it's time to refresh your hardware. Trust us.
.
|
|
|
|
| User: "" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 01:40:44 PM |
|
|
In article <1156091234.820969.198850@h48g2000cwc.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
Ben Newsam wrote:
On Sun, 20 Aug 2006 13:42:54 GMT, "Sorcerer"
<Headmaster@hogwarts.physics_a> wrote:
"cnctut" <cnctutwiler@wmconnect.com> wrote in message
news:1156050446.429728.261790@75g2000cwc.googlegroups.com...
| I'm sure we've come a long way since the old shoe store X-ray
| machines--and those X-ray glasses sold years ago on the back page of
| comics. ;-))
Egads... if you remember those then you are not so young anymore.
Still, it was fun wiggling green metatarsals and phalanges.
I remember them. They were banned because of being dangerous. I have
often wondered just how dangerous they were, my little tootsies were
shoved into one of those several times.
--
Posted via a free Usenet account from http://www.teranews.com
//
Ben,
I don't know how dangerous they were--my feet still look
normal--perhaps the risk was more for employees who work around the
machines. I did see one recently that was still being used at the foot
doctors office (when my wife broke her foot.) Not sure they had any
practical value for selling shoes, other than as a sales gimmic--but I
never sold shoes--so I don't know for sure. I would like to have one in
the garage for various projects I'll never get to.
If everything is as dangerous as some suggest--mercury, lead etc--I
should have been dead years ago. I experimented as a child with all
that stuff--vapors, touching, etc. Now one drop of mercury shutsdown a
school until HAZMAT cleans it up.
Yep. Upon discovering (or, rather, rediscovering) that keeping people
scared is a working path to wealth and power, modern societies proceed
to scare their citizens shitless of pretty much everything.
Extrapolating, we can foresee in a not too far future a near shutdown
of any useful activity. Fortunately, plain extrapolations always
break down in the long run, so there is hope yet.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
.
|
|
|
| User: "cnctut" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 01:51:00 PM |
|
|
wrote:
In article <1156091234.820969.198850@h48g2000cwc.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
Ben Newsam wrote:
On Sun, 20 Aug 2006 13:42:54 GMT, "Sorcerer"
<Headmaster@hogwarts.physics_a> wrote:
"cnctut" <cnctutwiler@wmconnect.com> wrote in message
news:1156050446.429728.261790@75g2000cwc.googlegroups.com...
| I'm sure we've come a long way since the old shoe store X-ray
| machines--and those X-ray glasses sold years ago on the back page of
| comics. ;-))
Egads... if you remember those then you are not so young anymore.
Still, it was fun wiggling green metatarsals and phalanges.
I remember them. They were banned because of being dangerous. I have
often wondered just how dangerous they were, my little tootsies were
shoved into one of those several times.
--
Posted via a free Usenet account from http://www.teranews.com
//
Ben,
I don't know how dangerous they were--my feet still look
normal--perhaps the risk was more for employees who work around the
machines. I did see one recently that was still being used at the foot
doctors office (when my wife broke her foot.) Not sure they had any
practical value for selling shoes, other than as a sales gimmic--but I
never sold shoes--so I don't know for sure. I would like to have one in
the garage for various projects I'll never get to.
If everything is as dangerous as some suggest--mercury, lead etc--I
should have been dead years ago. I experimented as a child with all
that stuff--vapors, touching, etc. Now one drop of mercury shutsdown a
school until HAZMAT cleans it up.
Yep. Upon discovering (or, rather, rediscovering) that keeping people
scared is a working path to wealth and power, modern societies proceed
to scare their citizens shitless of pretty much everything.
Extrapolating, we can foresee in a not too far future a near shutdown
of any useful activity. Fortunately, plain extrapolations always
break down in the long run, so there is hope yet.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Mati,
Right on target! If he lawyers have their way with fatty foods, I'm
going to really miss a "Big Mac" and fries. Oh, and I like WalMart
too--darn. ;-))
VR
Tut
.
|
|
|
| User: "" |
|
| Title: Re: Weight & mass question |
21 Aug 2006 04:24:34 AM |
|
|
In article <1156099860.460594.48370@74g2000cwt.googlegroups.com>,
"cnctut" <cnctutwiler@wmconnect.com> wrote:
mmeron@cars3.uchicago.edu wrote:
In article <1156091234.820969.198850@h48g2000cwc.googlegroups.com>,
"cnctut" <cnctutwiler@wmconnect.com> writes:
Ben Newsam wrote:
On Sun, 20 Aug 2006 13:42:54 GMT, "Sorcerer"
<Headmaster@hogwarts.physics_a> wrote:
"cnctut" <cnctutwiler@wmconnect.com> wrote in message
news:1156050446.429728.261790@75g2000cwc.googlegroups.com...
| I'm sure we've come a long way since the old shoe store X-ray
| machines--and those X-ray glasses sold years ago on the back page of
| comics. ;-))
Egads... if you remember those then you are not so young anymore.
Still, it was fun wiggling green metatarsals and phalanges.
I remember them. They were banned because of being dangerous. I have
often wondered just how dangerous they were, my little tootsies were
shoved into one of those several times.
--
Posted via a free Usenet account from http://www.teranews.com
//
Ben,
I don't know how dangerous they were--my feet still look
normal--perhaps the risk was more for employees who work around the
machines. I did see one recently that was still being used at the foot
doctors office (when my wife broke her foot.) Not sure they had any
practical value for selling shoes, other than as a sales gimmic--but I
never sold shoes--so I don't know for sure. I would like to have one in
the garage for various projects I'll never get to.
If everything is as dangerous as some suggest--mercury, lead etc--I
should have been dead years ago. I experimented as a child with all
that stuff--vapors, touching, etc. Now one drop of mercury shutsdown a
school until HAZMAT cleans it up.
Yep. Upon discovering (or, rather, rediscovering) that keeping people
scared is a working path to wealth and power, modern societies proceed
to scare their citizens shitless of pretty much everything.
Extrapolating, we can foresee in a not too far future a near shutdown
of any useful activity. Fortunately, plain extrapolations always
break down in the long run, so there is hope yet.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Mati,
Right on target! If he lawyers have their way with fatty foods, I'm
going to really miss a "Big Mac" and fries. Oh, and I like WalMart
too--darn. ;-))
And from the latest news I heard, hot dogs. And all because
people don't cook their food before they eat it.
/BAH
.
|
|
|
|
|
| User: "" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 05:26:01 PM |
|
|
In article <1156099860.460594.48370@74g2000cwt.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
mmeron@cars3.uchicago.edu wrote:
In article <1156091234.820969.198850@h48g2000cwc.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
Ben Newsam wrote:
On Sun, 20 Aug 2006 13:42:54 GMT, "Sorcerer"
<Headmaster@hogwarts.physics_a> wrote:
"cnctut" <cnctutwiler@wmconnect.com> wrote in message
news:1156050446.429728.261790@75g2000cwc.googlegroups.com...
| I'm sure we've come a long way since the old shoe store X-ray
| machines--and those X-ray glasses sold years ago on the back page of
| comics. ;-))
Egads... if you remember those then you are not so young anymore.
Still, it was fun wiggling green metatarsals and phalanges.
I remember them. They were banned because of being dangerous. I have
often wondered just how dangerous they were, my little tootsies were
shoved into one of those several times.
--
Posted via a free Usenet account from http://www.teranews.com
//
Ben,
I don't know how dangerous they were--my feet still look
normal--perhaps the risk was more for employees who work around the
machines. I did see one recently that was still being used at the foot
doctors office (when my wife broke her foot.) Not sure they had any
practical value for selling shoes, other than as a sales gimmic--but I
never sold shoes--so I don't know for sure. I would like to have one in
the garage for various projects I'll never get to.
If everything is as dangerous as some suggest--mercury, lead etc--I
should have been dead years ago. I experimented as a child with all
that stuff--vapors, touching, etc. Now one drop of mercury shutsdown a
school until HAZMAT cleans it up.
Yep. Upon discovering (or, rather, rediscovering) that keeping people
scared is a working path to wealth and power, modern societies proceed
to scare their citizens shitless of pretty much everything.
Extrapolating, we can foresee in a not too far future a near shutdown
of any useful activity. Fortunately, plain extrapolations always
break down in the long run, so there is hope yet.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Mati,
Right on target! If he lawyers have their way with fatty foods, I'm
going to really miss a "Big Mac" and fries. Oh, and I like WalMart
too--darn. ;-))
I'll raise a glass to this. Cheers.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
.
|
|
|
|
|
| User: "cnctut" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 09:23:15 AM |
|
|
Sorcerer wrote:
"cnctut" <cnctutwiler@wmconnect.com> wrote in message
news:1156050446.429728.261790@75g2000cwc.googlegroups.com...
|
| wrote:
| > In article <1156034461.429716.81080@b28g2000cwb.googlegroups.com>,
"cnctut" <cnctutwiler@wmconnect.com> writes:
| > >
| > > wrote:
| > >> Tut wrote:
| > >> >Mati--
| > >> >
| > >> >You are correct--but to say "Lurch, at 91 kg you 'mass' to much,
just
| > >> >doesn't sound right does it. ;-))
| > >>
| > >> Yes, and that's why we've a perfectly good word, i.e. "weigh".
That's
| > >> what I said above.
| > >>
| > >> Mati Meron | "When you argue with a fool,
| > >> | chances are he is doing just the
same"
| > >
| > >Mati,
| > >
| > >Just having some fun with you--please don't zap me with a laser. :-))
| > >
| > No lasers, promise. I'm using x-ray beams:-) You won't believe what
| > beam you can get with a decent undulator.
| >
| > Mati Meron | "When you argue with a fool,
| > | chances are he is doing just the
same"
|
| Tut writes:
|
| I'm sure we've come a long way since the old shoe store X-ray
| machines--and those X-ray glasses sold years ago on the back page of
| comics. ;-))
Egads... if you remember those then you are not so young anymore.
Still, it was fun wiggling green metatarsals and phalanges.
Androcles
Tut writes:
Hot computers in my day were new analogs and 3" Picket slide-rulers.
;-))
Tut
.
|
|
|
| User: "Sorcerer" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 09:44:44 AM |
|
|
"cnctut" <cnctutwiler@wmconnect.com> wrote in message
news:1156083795.140752.87160@75g2000cwc.googlegroups.com...
|
| Sorcerer wrote:
| > "cnctut" <cnctutwiler@wmconnect.com> wrote in message
| > news:1156050446.429728.261790@75g2000cwc.googlegroups.com...
| > |
| > | wrote:
| > | > In article <1156034461.429716.81080@b28g2000cwb.googlegroups.com>,
| > "cnctut" <cnctutwiler@wmconnect.com> writes:
| > | > >
| > | > > wrote:
| > | > >> Tut wrote:
| > | > >> >Mati--
| > | > >> >
| > | > >> >You are correct--but to say "Lurch, at 91 kg you 'mass' to much,
| > just
| > | > >> >doesn't sound right does it. ;-))
| > | > >>
| > | > >> Yes, and that's why we've a perfectly good word, i.e. "weigh".
| > That's
| > | > >> what I said above.
| > | > >>
| > | > >> Mati Meron | "When you argue with a fool,
| > | > >> | chances are he is doing just
the
| > same"
| > | > >
| > | > >Mati,
| > | > >
| > | > >Just having some fun with you--please don't zap me with a laser.
:-))
| > | > >
| > | > No lasers, promise. I'm using x-ray beams:-) You won't believe
what
| > | > beam you can get with a decent undulator.
| > | >
| > | > Mati Meron | "When you argue with a fool,
| > | > | chances are he is doing just the
| > same"
| > |
| > | Tut writes:
| > |
| > | I'm sure we've come a long way since the old shoe store X-ray
| > | machines--and those X-ray glasses sold years ago on the back page of
| > | comics. ;-))
| >
| > Egads... if you remember those then you are not so young anymore.
| > Still, it was fun wiggling green metatarsals and phalanges.
| > Androcles
|
| Tut writes:
|
| Hot computers in my day were new analogs and 3" Picket slide-rulers.
| ;-))
http://www.sliderulemuseum.com/Pickett/S472_AssocSpringCardboardSlideRule_1947.jpgLog tables were better, but what I wanted was a helical slide rule.Logarithms were originally invented by John Napier in 1614. In 1620, EdmundGunter first noted that a logarithmic scale could be used in combinationwith a compass for measuring out distances along it to performmultiplication. And then the slide rule itself was invented in 1632 byWilliam Oughtred. The modern form of the slide rule, in which two pairs ofscales slide against each other, so that the rule is composed of a sliderand a stock, was at one time credited to Seth Partridge in 1657, but it isnow known he was describing an earlier invention, believed to be that ofRobert Bissaker in 1654.Unlike logarithm tables, which remained an important aid to calculation eversince their invention and until the emergence of the pocket calculator. theslide rule appears to have languished in relative obscurity from Oughtred toMannheim. Although a few scientists and engineers did make use of the sliderule, its chief popularity in the first part of its existence appears tohave been as a tool for calculating taxes on barrels of alcoholic beveragesin Britain.http://www.quadibloc.com/math/sr03.htmThis is the one I owned: http://home.vicnet.net.au/~wolff/calculators/sliderules/Aristo0903New-IMG_0262-5.jpg
.
|
|
|
|
|
| User: "" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 12:10:54 AM |
|
|
In article <1156050446.429728.261790@75g2000cwc.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
mmeron@cars3.uchicago.edu wrote:
In article <1156034461.429716.81080@b28g2000cwb.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
mmeron@cars3.uchicago.edu wrote:
Tut wrote:
Mati--
You are correct--but to say "Lurch, at 91 kg you 'mass' to much, just
doesn't sound right does it. ;-))
Yes, and that's why we've a perfectly good word, i.e. "weigh". That's
what I said above.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Mati,
Just having some fun with you--please don't zap me with a laser. :-))
No lasers, promise. I'm using x-ray beams:-) You won't believe what
beam you can get with a decent undulator.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Tut writes:
I'm sure we've come a long way since the old shoe store X-ray
machines--and those X-ray glasses sold years ago on the back page of
comics. ;-))
Yeah, we did come a long way. The new machines are of a different
league alltogether.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
.
|
|
|
| User: "cnctut" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 12:20:52 AM |
|
|
wrote:
In article <1156050446.429728.261790@75g2000cwc.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
mmeron@cars3.uchicago.edu wrote:
In article <1156034461.429716.81080@b28g2000cwb.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
mmeron@cars3.uchicago.edu wrote:
Tut wrote:
Mati--
You are correct--but to say "Lurch, at 91 kg you 'mass' to much, just
doesn't sound right does it. ;-))
Yes, and that's why we've a perfectly good word, i.e. "weigh". That's
what I said above.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Mati,
Just having some fun with you--please don't zap me with a laser. :-))
No lasers, promise. I'm using x-ray beams:-) You won't believe what
beam you can get with a decent undulator.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Tut writes:
I'm sure we've come a long way since the old shoe store X-ray
machines--and those X-ray glasses sold years ago on the back page of
comics. ;-))
Yeah, we did come a long way. The new machines are of a different
league alltogether.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Mati,
We must be the only ones up--nope, Tom Potter just checked in on PD's
Crank post. Later.
Tut
.
|
|
|
|
| User: "" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 01:21:50 AM |
|
|
In article <1156051252.189866.179820@m73g2000cwd.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
mme...@cars3.uchicago.edu wrote:
In article <1156050446.429728.261790@75g2000cwc.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
mmeron@cars3.uchicago.edu wrote:
In article <1156034461.429716.81080@b28g2000cwb.googlegroups.com>, "cnctut" <cnctutwiler@wmconnect.com> writes:
mmeron@cars3.uchicago.edu wrote:
Tut wrote:
Mati--
You are correct--but to say "Lurch, at 91 kg you 'mass' to much, just
doesn't sound right does it. ;-))
Yes, and that's why we've a perfectly good word, i.e. "weigh". That's
what I said above.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Mati,
Just having some fun with you--please don't zap me with a laser. :-))
No lasers, promise. I'm using x-ray beams:-) You won't believe what
beam you can get with a decent undulator.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Tut writes:
I'm sure we've come a long way since the old shoe store X-ray
machines--and those X-ray glasses sold years ago on the back page of
comics. ;-))
Yeah, we did come a long way. The new machines are of a different
league alltogether.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Mati,
We must be the only ones up--nope, Tom Potter just checked in on PD's
Crank post. Later.
Tom Potter? You're wasting your time:-)
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
.
|
|
|
|
|
| User: "cnctut" |
|
| Title: Re: Weight & mass question |
19 Aug 2006 07:23:14 PM |
|
|
PD wrote:
(some snipped)
I'll gloss over a historical artifact that a "pound" has been used both
as a unit of mass and as a unit of force (weight), and adopt the
convention that the English system uses "slugs" as units of mass and
"pounds" as units of weight.
PD,
You are kind and generous. ;-)))
Tut
.
|
|
|
|
| User: "Mike" |
|
| Title: Re: Weight & mass question |
19 Aug 2006 04:26:03 PM |
|
|
Charlie Johnson wrote:
Hi all,
I am confused, as usual. Say I weigh 200 lbs. measured by a typical
bathroom scale. If I convert that to newtons, I get (4.45 N)(220 lbs.) =
890 newtons. Now, to find my mass, I divide 890 N / 9.8 m/s^2 to get 91 kg.
But, if I convert my 200 lbs. to kilograms by the coversion 2.2 lbs / kg, I
get 91 kg. How can my weight be the same as my mass, if weight is mass x
acceleration?
What am I doing wrong here? Please help the befuddled!
Simply because, although spring scales measure force, they are
calibrated to read mass, assuming a given g level. So what the scale
reads is not pound-force but just pounds, i.e. mass.
Note that your conversion factor 9.8 m/s^2 / 4.45 N is equal to about
2.2 lbs/Kg, so in this case the two conversions you performed are
equivalent given the fact the your reading is actually mass and not
force.
Mike
T.I.A.
Lurch
.
|
|
|
|
| User: "helloworld" |
|
| Title: Re: Weight & mass question |
20 Aug 2006 07:32:19 AM |
|
|
The unnies wrote on 19 aug 2006 :
First of all, please realise that ""mass"" and ""weight"" are NOT the
same.
They are two entirely different concepts .
Before the advent of Realtivity and Quantum physics, Mass was variously
conceived and defined as the ''matter-content'' in an object or ''
reistance to motion'' ( cause of inertia)
whereas, ''weight'' is due to acceleration due to gravity acting on
mass .On earth , we have to multiply with a factor of 9.5 approx to
get your weight in Kgs, on Moon ,by a factor 1/ 6 th of it. You feel
weightless if you are orbiting round the earth in an artificial
satellite , but your mass does not change . You dont become mass-less
(ubless, perhaps, you are an electromagnetic wave )
The correct unit of measurement of mass is (kg-mass)units and of weight
is (kg-mtr / sec ^ 2 ) .
We normally express loosely both as KGs and cause the confusion you had
weight is a '' force'' ; something applied to mass; whereas mass is
some intrinsic quality inherent in matter itself not attributable to
anything external to the object ,Mass was considered to be almost the
defining characteristic of matter and nothing to do with force as such,
except that, the ''force'' experienced by a ''mass'' is depended
upon mass and acceleration with which the mass moves. One can feel
one's mass only if there exists a '' resultant change '' to motion.
Mass is then felt as a proportional weight, proportional to the
resultant acceleration.the body is sunjected to . If there is no
resultant acceleration , there is no force expereinecd. .Thats why a
body moving in uniform velocity is not experiencing any force or, any
weight when you are going round the earth in an artificial satellite
,. There has to be a non-zero resultant change in velocity either in
magnitude or in direction or both for experiencing your mass as some
weight. But for the existence .of mass itself there is no need for
velocity or acceleration. Anyhow that was the concept in Newtonian
physics before relativity physics came.
Note, weight is a vector quantity whereas mass is a scalar quantity,
even in Newtonian physics..
According to Relativity principles ,Mass ( and NOT weight) can change
perceptibly if it moves near the velocity of light. This is due to
sticking on with the assumption that the speed of light is a universl
constant.for which there is no experimental evidence at all. But this
assumptin was found to be most useful for ease of calculations and
for offering mathematical explanations for odd details of astronomical
phenomena, in the macrouniverse.
However, this assumption almost fails to hold good at microcosm in the
subatomic quantum science. But that is another story
For keeping the speed of light constant we had to bend and stretch and
contort space .But contorting space is easier to do than keeping the
speed pf light varying which means we have to contort '' time'', a much
more daunting task So we preferred to bend space and keep light ( or,
time) moving straight and at a constant speed making velocity of light
a scalar quantity ). . Any variation in the speed of light was ascribed
to configuration of space or the medium through which light had to
pass in that region .
The concept of Mass is highly technical and even philosophical. .The
concept of weight is more practical .
Some phsicists say that there is more to ''mass'' than mere '
matter-content''. The final constituents of matter consists of
non-matter or non-material entities too, such as quarks and Higgs
bosons . We all know that there is a lot of empty space ( or empty
fluctuating fields) within the apparent hardness of solid matter , To
make a crude example,the otherwise shapeless air inside a balloon gives
tha balloon its shape. But again that is another story.
Light has sometimes mass and weight but sometimes neither . Light
itself behaves like lumpen material particles with a quantum of mass
(manifesting as photons as in photoelectric effect , for which
concept einstein got his prize) and sometimes as pure radiating
non-material energy waves without any mass ( as in young's double slit
experiment where we have to account for interference effects ).
Anything which has energy , has mass . So ''mass'' is the
''energy-content in matter'' or, the energy-content in radiating
waves,and not just matter content in any material.In this sense
''mass'' is not always something that resists motion but sometimes that
entity / that energy, that causes motion, as in light.who knows? .
There is no energy or mass conservation but there is only energy-mass
conservation .
I hope that I have been able to address to your confusion and, that you
are no more befuddled about these two concepts. now.
the unnies.
Charlie Johnson wrote:
Hi all,
I am confused, as usual. Say I weigh 200 lbs. measured by a typical
bathroom scale. If I convert that to newtons, I get (4.45 N)(220 lbs.) =
890 newtons. Now, to find my mass, I divide 890 N / 9.8 m/s^2 to get 91 kg.
But, if I convert my 200 lbs. to kilograms by the coversion 2.2 lbs / kg, I
get 91 kg. How can my weight be the same as my mass, if weight is mass x
acceleration?
What am I doing wrong here? Please help the befuddled!
T.I.A.
Lurch
.
|
|
|
|
|
Related Articles |
|
|
