Science > Physics > Androcles' long-winded solution to the mosquito problem
| Topic: |
Science > Physics |
| User: |
"Randy Poe" |
| Date: |
07 Jan 2005 02:51:33 PM |
| Object: |
Androcles' long-winded solution to the mosquito problem |
Androcles wrote:
"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105046914.966673.254950@z14g2000cwz.googlegroups.com...
MY equation applies equally well to a bouncing ball or a mosquito
From the standpoint of an observer on the road, we
can say the following.
Same velocity in both directions:
- light
- sound through stationary air
- mosquito
Different velocity in each direction:
- sound through enclosed (moving) air
- bouncing ball
The equation I was talking about applies in the first
case (same ground speed in both directions). No equation
applies to both.
As I hope you realized by now, by the time you wrote down
the actual solution to the mosquito problem, you ended
up with my equation. Or have you not realized yet
that you worked out L/(u-v) + L/(u+v)?
If not, your equation is worthless.
The time for the round trip, on the plane, in the bus, on the back
of the flatbed truck, no matter what vehicle we use, is
t = 2d/c. Right or wrong?
Wrong. See your solution for the mosquito.
- Randy
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 11:44:52 AM |
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"Daryl McCullough" <daryl@atc-nycorp.com> wrote in message
news:cru9up0inn@drn.newsguy.com...
Androcles says...
I KNOW I can handle algebra and frames, and I know you have no
idea what a frame is.
What I know is that you don't need to know anything about frames
or Galilean transformations in order to solve for t in terms of
L, u and v given
1. D_m = D_j + L
2. u t = D_m
3. v t = D_j
You think that it is impossible
to solve a system of three equations without using a coordinate
transformation?
You can solve for t if you assume it is invariant.
Invariant means that it has the same value in all frames.
That's right, ducky. Time is the same in all frames.
Since
we're only computing it in *one* frame, it isn't necessary to
assume it is invariant.
But you are not. The moment you subtracted (ut) you were performing
the Galilean Transform.
In the moving frame you have 2 velocities and one distance,
in the stationary frame just one velocity and two distances.
Too dumb to see that?
Once again, do you think it is impossible to solve a system
of three equations and three unknowns without using a coordinate
transformation, and without making assumptions about invariance?
Absolutely. You are using invariant time in the pathetic little problem
you posed.
--
Daryl McCullough
Ithaca, NY
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| User: "Franz Heymann" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 04:53:11 PM |
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"Androcles" <dummy@dummy.net> wrote in message
news:oazEd.99815$Z7.78006@fe2.news.blueyonder.co.uk...
"Daryl McCullough" <daryl@atc-nycorp.com> wrote in message
news:cru9up0inn@drn.newsguy.com...
Androcles says...
I KNOW I can handle algebra and frames, and I know you have no
idea what a frame is.
What I know is that you don't need to know anything about frames
or Galilean transformations in order to solve for t in terms of
L, u and v given
1. D_m = D_j + L
2. u t = D_m
3. v t = D_j
You think that it is impossible
to solve a system of three equations without using a coordinate
transformation?
You can solve for t if you assume it is invariant.
Invariant means that it has the same value in all frames.
That's right, ducky. Time is the same in all frames.
Since
we're only computing it in *one* frame, it isn't necessary to
assume it is invariant.
But you are not. The moment you subtracted (ut) you were performing
the Galilean Transform.
In the moving frame you have 2 velocities and one distance,
in the stationary frame just one velocity and two distances.
Too dumb to see that?
..Get yourself a piece of graph paper. Sit still Choose an origin.
Choose scales for measuring t horizontally and x vertically.
On these you may now plot position - time graphs *as measure by you in
your coordinates*. I presume you know enough coordinate geometry to
draw graphs, all straight lines, of the positions of the first bloke,
the second bloke and the mosquito, using the velocities given in the
problem. Note the time at which the graph og the mosquito intersects
that of the second bloke. Voila, the forward time. From that point
draw the graph of the mosquito on its return path, i.e. with a
reversed velocity. Find the point where it intersects the graph of
the first man. Voila the return time and the total time.
There will be mo change in frame. All will be as measured by you,
sitting still.
The CapeTown to Simonstown suburban service ran frequent trains in
both directions. At any moment, there would be around 10 or so trains
on the route. The time-tables were determined by the fact that all
train crossings had to occur *only* at any one of the 15
(approximately) stations, since they did not have double lines, except
at stations. The timings were obtained by juggling the position-time
graphs of all the trains. The blokes who did it knew nothing about
either different frames or about Galilean transformations of about
Lotentz transformations. They knew enough simple
coordinate geometry to do the job. You seem to not even have the
knowledge to handle 3 objects simultaneously without making a hash of
it.
Franz
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 12:10:38 PM |
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Androcles says...
Since
we're only computing it in *one* frame, it isn't necessary to
assume it is invariant.
But you are not. The moment you subtracted (ut) you were performing
the Galilean Transform.
Let's consider a different problem: Let u = the rate at which I
spend my money. Let v = the rate at which I earn money. Let L = the
amount of money I have in the bank. How long will it take before my
bank account is empty?
I would set up the equation as
ut = vt + L
and solve for t. You say I'm doing a Galilean transform? Whose
frame of reference am I transforming to?
--
Daryl McCullough
Ithaca, NY
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 12:52:32 PM |
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"Daryl McCullough" <daryl@atc-nycorp.com> wrote in message
news:crugeu016td@drn.newsguy.com...
Androcles says...
Since
we're only computing it in *one* frame, it isn't necessary to
assume it is invariant.
But you are not. The moment you subtracted (ut) you were performing
the Galilean Transform.
Let's consider a different problem: Let u = the rate at which I
spend my money. Let v = the rate at which I earn money. Let L = the
amount of money I have in the bank. How long will it take before my
bank account is empty?
I would set up the equation as
ut = vt + L
and solve for t. You say I'm doing a Galilean transform? Whose
frame of reference am I transforming to?
From the ground frame in which two distances and one
velocity is used to the moving frame in which one distance and
two velocities are used. Time is invariant, so you are allowed
to use t in either frame.
Androcles
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| User: "Dirk Van de moortel" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 01:22:10 PM |
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"Androcles" <dummy@dummy.net> wrote in message news:Q9AEd.99992$Z7.75264@fe2.news.blueyonder.co.uk...
"Daryl McCullough" <daryl@atc-nycorp.com> wrote in message
news:crugeu016td@drn.newsguy.com...
Androcles says...
Since
we're only computing it in *one* frame, it isn't necessary to
assume it is invariant.
But you are not. The moment you subtracted (ut) you were performing
the Galilean Transform.
Let's consider a different problem: Let u = the rate at which I
spend my money. Let v = the rate at which I earn money. Let L = the
amount of money I have in the bank. How long will it take before my
bank account is empty?
I would set up the equation as
ut = vt + L
and solve for t. You say I'm doing a Galilean transform? Whose
frame of reference am I transforming to?
From the ground frame in which two distances and one
velocity is used to the moving frame in which one distance and
two velocities are used. Time is invariant, so you are allowed
to use t in either frame.
Androcles
Good one:
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/TeachApe.html
Title: "Teaching an ape"
Thanks, Daryl :-))
Dirk Vdm
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 01:13:40 PM |
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Androcles says...
"Daryl McCullough" <daryl@atc-nycorp.com> wrote
Let's consider a different problem: Let u = the rate at which I
spend my money. Let v = the rate at which I earn money. Let L = the
amount of money I have in the bank. How long will it take before my
bank account is empty?
I would set up the equation as
ut = vt + L
and solve for t. You say I'm doing a Galilean transform? Whose
frame of reference am I transforming to?
From the ground frame in which two distances and one
velocity is used to the moving frame in which one distance and
two velocities are used. Time is invariant, so you are allowed
to use t in either frame.
I think you had a short-circuit there. In the above, L is
an amount of money, not a distance.
--
Daryl McCullough
Ithaca, NY
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| User: "Randy Poe" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
09 Jan 2005 12:49:14 AM |
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Androcles wrote:
Why should I bother, it is only high school algebra.
vt is the distance the mosquito moves,
ut is the distance Sam moves
L is the fixed distance Joe is from Sam.
vt = ut+L. Solve for t.
Excellent. Notice how there was no need to consider
different frames of reference in order to do this problem,
which has nothing to do with relativity. Nor was there
any need to bring in the equation you're obsessed with
involving tau(x',y,z,t).
Now, can you do the algebra and solve for t?
Please try to stay focused. Not everything is about
relativity.
- Randy
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
09 Jan 2005 11:04:16 AM |
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"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105253354.081778.258250@c13g2000cwb.googlegroups.com...
Androcles wrote:
Why should I bother, it is only high school algebra.
vt is the distance the mosquito moves,
ut is the distance Sam moves
L is the fixed distance Joe is from Sam.
vt = ut+L. Solve for t.
Excellent. Notice how there was no need to consider
different frames of reference in order to do this problem,
which has nothing to do with relativity.
So why did you convert to the moving frame then?
You are as bad as McCullough. He doesn't know what a frame
is either.
80/5 + 20/5 = 20 in the ground frame. You used
32/2 and 32/8 = 20 in the moving frame.
The ground frame has two distances and one velocity.
The moving frame has one distance and two velocities
YOU converted from the ground frame and calculated time
in the moving frame. You did that by saying v-u and v+u,
creating the two velocities 2 and 8.
You don't know what a frame is.
Nor was there
any need to bring in the equation you're obsessed with
involving tau(x',y,z,t).
Now, can you do the algebra and solve for t?
Please try to stay focused. Not everything is about
relativity.
LOL. When you know what a frame is, aand how to convert from
one to another, we'll talk about relativity.
I'm bored. Bye.
Androcles.
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| User: "Randy Poe" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
09 Jan 2005 07:30:02 PM |
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Androcles wrote:
"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105253354.081778.258250@c13g2000cwb.googlegroups.com...
Androcles wrote:
Why should I bother, it is only high school algebra.
vt is the distance the mosquito moves,
ut is the distance Sam moves
L is the fixed distance Joe is from Sam.
vt = ut+L. Solve for t.
Excellent. Notice how there was no need to consider
different frames of reference in order to do this problem,
which has nothing to do with relativity.
So why did you convert to the moving frame then?
Don't put words (or derivations) in my mouth.
Do you believe that vt = ut + L is the equation for
the time at which the mosquito flying forward intersects
the walker, if v=velocity of mosquito and u=velocity of
walker?
If so, do you understand that the value of t which
solves this equation is t = L/(v-u)?
It has nothing to do with "converting to the moving
frame". It's just solving an equation which you presented.
I'm beginning to think you really haven't taken algebra,
and don't understand that the solution to
vt = ut + L
is
t = L/(v-u)
Is that the case? Is that why you think the appearance
of (v-u) implies I've changed frames?
It doesn't. It's just algebra. Try it with some different
values of v, u, and L.
For instance, v=10, u=6, L=40. This gives t = 40/(10-6) = 10
Notice that this value of t satisfies vt = ut + L
10*10 = 6*10 + 40
- Randy
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 05:55:39 AM |
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"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105320602.494652.255540@c13g2000cwb.googlegroups.com...
Androcles wrote:
"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105253354.081778.258250@c13g2000cwb.googlegroups.com...
Androcles wrote:
Why should I bother, it is only high school algebra.
vt is the distance the mosquito moves,
ut is the distance Sam moves
L is the fixed distance Joe is from Sam.
vt = ut+L. Solve for t.
Excellent. Notice how there was no need to consider
different frames of reference in order to do this problem,
which has nothing to do with relativity.
So why did you convert to the moving frame then?
Don't put words (or derivations) in my mouth.
If the cap fits, wear it.
Do you believe that vt = ut + L is the equation for
the time at which the mosquito flying forward intersects
the walker, if v=velocity of mosquito and u=velocity of
walker?
If so, do you understand that the value of t which
solves this equation is t = L/(v-u)?
You've just converted to the moving frame, preserving only
time. You don't even realize you are doing it. The distance
80 in the ground frame has vanished, you've replaced it with 32.
The speed v = 5 has vanished, you've replaced it with 2.
It has nothing to do with "converting to the moving
frame".
Oh yes it does. You just haven't realized it. If I asked
you "What is the speed of the mosquito in the moving frame?"
would you say "5 fps"?
It's just solving an equation which you presented.
Converting coordinates from one frame to the other IS
just an equation.
I'm beginning to think you really haven't taken algebra,
You don't think at all.
and don't understand that the solution to
vt = ut + L
is
t = L/(v-u)
Is that the case?
The case is that if I asked the distance the mosquito
flies in the ground frame the answer is 80 at 5 fps, and
if I ask the distance the mosquito flies in the moving frame
the answer is 32 at 2 fps.
You subtracted the distance 'ut' from L. That IS the conversion.
L = x - ut, or 32 = 80-48 in this case, is the Galilean Transform.
And You used it.
vt = ut + L is ground frame.
Subtract ut from each side of the equation.
vt-ut = (ut + L)-ut
= L.
There it is, you've just used the Galilean transform.
You are not JUST solving an equation, as you seem
to think. You are converting coordinates between frames.
Is that why you think the appearance
of (v-u) implies I've changed frames?
It doesn't. It's just algebra. Try it with some different
values of v, u, and L.
Coordinate conversion between frames is just algebra.
It is you that is too thick to see it, not I.
Androcles.
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| User: "Randy Poe" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 06:18:53 AM |
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Androcles wrote:
"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105320602.494652.255540@c13g2000cwb.googlegroups.com...
Do you believe that vt = ut + L is the equation for
the time at which the mosquito flying forward intersects
the walker, if v=velocity of mosquito and u=velocity of
walker?
If so, do you understand that the value of t which
solves this equation is t = L/(v-u)?
You've just converted to the moving frame, preserving only
time. You don't even realize you are doing it. The distance
80 in the ground frame has vanished, you've replaced it with 32.
It has not. This is just a rearrangment of the
equation vt = ut + L. Do you believe that equation or
not?
This equation starts from saying two things. First,
it says, the distance traveled by the mosquito is
vt. Since it turns out t = 16 and v = 5, then this
equation has on the left-hand side the expression
vt = 16 * 5 = 80.
The speed v = 5 has vanished, you've replaced it with 2.
No, I haven't replaced it. The equation on the left hand
side shows "vt", which contains v and which has the value
of "80" for these numbers.
The right hand side of this equation is "ut + L". That
expresses in the stationary frame that after time t,
the walker has advanced a distance ut, because he is
moving at velocity u, plus the distance L that he was
originally located. Thus, at time t, the walker is at
position ut + L. Since it turns out that t is 16, then
this expression give 3*16 + 32 = 80.
So again, the 80 pops up, and it uses the value of
3 which is in the stationary frame, the only one
we are concerned with.
Do you believe that vt and ut + L are values in the
stationary frame? Do you believe the equation
vt = ut + L?
Do you understand that all of the following are the
same equation? That if one of them is a relationship
between things in the stationary frame, then all of them
are?
vt = ut + L
v = u + L/t
vt - ut = L
(v-u)t = L
L = (v-u)t
u = v - L/t
- Randy
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 07:10:58 AM |
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"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105359533.745941.79150@c13g2000cwb.googlegroups.com...
Androcles wrote:
"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105320602.494652.255540@c13g2000cwb.googlegroups.com...
Do you believe that vt = ut + L is the equation for
the time at which the mosquito flying forward intersects
the walker, if v=velocity of mosquito and u=velocity of
walker?
If so, do you understand that the value of t which
solves this equation is t = L/(v-u)?
You've just converted to the moving frame, preserving only
time. You don't even realize you are doing it. The distance
80 in the ground frame has vanished, you've replaced it with 32.
It has not. This is just a rearrangment of the
equation vt = ut + L.
Do you believe that equation or not?
This equation starts from saying two things. First,
it says, the distance traveled by the mosquito is
vt.
In the ground frame.
Since it turns out t = 16 and v = 5, then this
equation has on the left-hand side the expression
vt = 16 * 5 = 80.
Well done. The distance in the ground frame is 80.
The speed v = 5 has vanished, you've replaced it with 2.
No, I haven't replaced it.
Yes you did.
The equation on the left hand
side shows "vt", which contains v and which has the value
of "80" for these numbers.
Correct.
The right hand side of this equation is "ut + L".
Correct, so it too has the value 80.
That
expresses in the stationary frame that after time t,
the walker has advanced a distance ut,
Correct, that is 48 ft.
because he is
moving at velocity u, plus the distance L that he was
originally located.
Correct, and L +48 = 80.
You are still doing well, staying in the ground frame.
Thus, at time t, the walker is at
position ut + L.
Very good. Jo is at coordinate x = 80 in the ground frame.
I knew you could do it.
Since it turns out that t is 16, then
this expression give 3*16 + 32 = 80.
Excellent. You've found the ground frame coordinate.
So again, the 80 pops up, and it uses the value of
3 which is in the stationary frame, the only one
we are concerned with.
Do you believe that vt and ut + L are values in the
stationary frame? Do you believe the equation
vt = ut + L?
Well, of course, ducky.
Do you understand that all of the following are the
same equation? That if one of them is a relationship
between things in the stationary frame, then all of them
are?
vt = ut + L
v = u + L/t
vt - ut = L
OOPS! You've just used the Galilean transform and converted
to moving frame coordinates. You subtracted ut.
L = x - ut.
Androcles.
(v-u)t = L
L = (v-u)t
u = v - L/t
- Randy
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 07:40:05 AM |
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Androcles says...
Do you believe that vt and ut + L are values in the
stationary frame? Do you believe the equation
vt = ut + L?
Well, of course, ducky.
Do you understand that all of the following are the
same equation? That if one of them is a relationship
between things in the stationary frame, then all of them
are?
vt = ut + L
v = u + L/t
vt - ut = L
OOPS! You've just used the Galilean transform and converted
to moving frame coordinates.
Okay, so you are under the impression that any time
you perform a subtraction, you are doing a coordinate
transformation. You believe that
vt = ut + L
is true in the ground frame, but the only way to *solve*
for t is to perform a coordinate transformation. Is that
what you really believe?
--
Daryl McCullough
Ithaca, NY
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 09:43:03 AM |
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"Daryl McCullough" <daryl@atc-nycorp.com> wrote in message
news:cru0jl02mq1@drn.newsguy.com...
Androcles says...
Do you believe that vt and ut + L are values in the
stationary frame? Do you believe the equation
vt = ut + L?
Well, of course, ducky.
Do you understand that all of the following are the
same equation? That if one of them is a relationship
between things in the stationary frame, then all of them
are?
vt = ut + L
v = u + L/t
vt - ut = L
OOPS! You've just used the Galilean transform and converted
to moving frame coordinates.
Okay, so you are under the impression that any time
you perform a subtraction, you are doing a coordinate
transformation. You believe that
vt = ut + L
is true in the ground frame, but the only way to *solve*
for t is to perform a coordinate transformation. Is that
what you really believe?
The only way to solve for t is for it to be invariant.
Androcles.
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 10:22:56 AM |
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Androcles says...
Okay, so you are under the impression that any time
you perform a subtraction, you are doing a coordinate
transformation. You believe that
vt = ut + L
is true in the ground frame, but the only way to *solve*
for t is to perform a coordinate transformation. Is that
what you really believe?
The only way to solve for t is for it to be invariant.
Why do you believe that? Do you think that it is impossible
to solve the above equation for v unless v is invariant? Well,
it's easy:
v = u + L/t
I solved for v. But v *isn't* invariant.
--
Daryl McCullough
Ithaca, NY
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 12:49:03 PM |
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"Daryl McCullough" <daryl@atc-nycorp.com> wrote in message
news:crua500j7m@drn.newsguy.com...
Androcles says...
Okay, so you are under the impression that any time
you perform a subtraction, you are doing a coordinate
transformation. You believe that
vt = ut + L
is true in the ground frame, but the only way to *solve*
for t is to perform a coordinate transformation. Is that
what you really believe?
The only way to solve for t is for it to be invariant.
Why do you believe that? Do you think that it is impossible
to solve the above equation for v unless v is invariant? Well,
it's easy:
v = u + L/t
I solved for v. But v *isn't* invariant.
Well done.
Neither is u, and neither is c. t is, though.
Androcles.
--
Daryl McCullough
Ithaca, NY
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 01:15:41 PM |
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Androcles says...
vt = ut + L
is true in the ground frame, but the only way to *solve*
for t is to perform a coordinate transformation. Is that
what you really believe?
The only way to solve for t is for it to be invariant.
Why do you believe that? Do you think that it is impossible
to solve the above equation for v unless v is invariant? Well,
it's easy:
v = u + L/t
I solved for v. But v *isn't* invariant.
Well done.
Neither is u, and neither is c. t is, though.
So you are agreeing now that whether t is invariant
or not has nothing to do with it. I can solve for v,
even though v is not invariant. I can solve for u,
even though u is not invariant. So why is it necessary
to assume t is invariant in order to solve for t?
--
Daryl McCullough
Ithaca, NY
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| User: "Randy Poe" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 08:16:30 AM |
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Daryl McCullough wrote:
vt = ut + L
v = u + L/t
vt - ut = L
OOPS! You've just used the Galilean transform and converted
to moving frame coordinates.
Okay, so you are under the impression that any time
you perform a subtraction, you are doing a coordinate
transformation. You believe that
vt = ut + L
is true in the ground frame, but the only way to *solve*
for t is to perform a coordinate transformation. Is that
what you really believe?
Apparently so, which makes me think that Androcles has
never had any formal mathematics or science education.
Which makes me feel sorry for him and reluctant to
point fun.
- Randy
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 10:20:54 AM |
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"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105366590.751592.183790@c13g2000cwb.googlegroups.com...
Daryl McCullough wrote:
vt = ut + L
v = u + L/t
vt - ut = L
OOPS! You've just used the Galilean transform and converted
to moving frame coordinates.
Okay, so you are under the impression that any time
you perform a subtraction, you are doing a coordinate
transformation. You believe that
vt = ut + L
is true in the ground frame, but the only way to *solve*
for t is to perform a coordinate transformation. Is that
what you really believe?
Apparently so, which makes me think that Androcles has
never had any formal mathematics or science education.
Which makes me feel sorry for him and reluctant to
point fun.
- Randy
And I felt sorry for Poe, he is unable to reason and can only parrot
what he has been indoctrinated in. But then I gave up feeling sorry
for the dumb clown when he called me idiotic.
But of course the moron he is talking to is equally dumb, so
best leave the two of them to own juice. Neither one can answer
a point I make, they both snip. Typical dumb relativists.
Androcles.
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| User: "Dirk Van de moortel" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 08:40:33 AM |
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"Randy Poe" <poespam-trap@yahoo.com> wrote in message news:1105366590.751592.183790@c13g2000cwb.googlegroups.com...
Daryl McCullough wrote:
vt = ut + L
v = u + L/t
vt - ut = L
OOPS! You've just used the Galilean transform and converted
to moving frame coordinates.
Okay, so you are under the impression that any time
you perform a subtraction, you are doing a coordinate
transformation. You believe that
vt = ut + L
is true in the ground frame, but the only way to *solve*
for t is to perform a coordinate transformation. Is that
what you really believe?
Apparently so, which makes me think that Androcles has
never had any formal mathematics or science education.
Of course he had a formal mathematics education.
He is a retired electronic engineer. Really, no kidding.
He is just extremely frustrated over the fact that he
never understood the basics of relativity.
He clearly sketched his history right here:
http://users.pandora.be/vdmoortel/dirk/Physics/Fumbles/AndArg.html
(that is almost 4 years ago)
Which makes me feel sorry for him and reluctant to
point fun.
But he is very stupid *and* playing a game with you and
Daryl (and Paul, and Jesse...).
It seems that - at least in his own eyes - he is winning it :-)
Dirk Vdm
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 08:50:55 AM |
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Dirk Van de moortel says...
Of course he had a formal mathematics education.
He is a retired electronic engineer. Really, no kidding.
He is just extremely frustrated over the fact that he
never understood the basics of relativity...
But he is very stupid *and* playing a game with you and
Daryl (and Paul, and Jesse...).
It seems that - at least in his own eyes - he is winning it :-)
Yes. I know. But on the other hand, it seems that actual physics
is only discussed in moderated groups such as sci.physics.research.
The only entertainment for moderated groups comes from arguments
with crackpots.
--
Daryl McCullough
Ithaca, NY
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| User: "Dirk Van de moortel" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 10:02:52 AM |
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"Daryl McCullough" <daryl@atc-nycorp.com> wrote in message news:cru4of02af@drn.newsguy.com...
Dirk Van de moortel says...
Of course he had a formal mathematics education.
He is a retired electronic engineer. Really, no kidding.
He is just extremely frustrated over the fact that he
never understood the basics of relativity...
But he is very stupid *and* playing a game with you and
Daryl (and Paul, and Jesse...).
It seems that - at least in his own eyes - he is winning it :-)
Yes. I know. But on the other hand, it seems that actual physics
is only discussed in moderated groups such as sci.physics.research.
The only entertainment for moderated groups comes from arguments
with crackpots.
I'm with you, if you replace "moderated" with "unmoderated" in the
last sentence :-)
Cheers and enjoy,
Dirk Vdm
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| User: "Randy Poe" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 08:13:48 AM |
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Androcles wrote:
The equation on the left hand
side shows "vt", which contains v and which has the value
of "80" for these numbers.
Correct.
The right hand side of this equation is "ut + L".
Correct, so it too has the value 80.
That
expresses in the stationary frame that after time t,
the walker has advanced a distance ut,
Correct, that is 48 ft.
How did you arrive at these numbers? Did you not
solve for t at some point? What did the process of
solving for t look like?
because he is
moving at velocity u, plus the distance L that he was
originally located.
Correct, and L +48 = 80.
You are still doing well, staying in the ground frame.
OK, so you agree that vt = ut + L is an equation
in the ground frame. The value of t that solves it
is the solution to this equation in the ground frame,
right?
What is that solution?
Thus, at time t, the walker is at
position ut + L.
Very good. Jo is at coordinate x = 80 in the ground frame.
I knew you could do it.
Since it turns out that t is 16, then
this expression give 3*16 + 32 = 80.
Excellent. You've found the ground frame coordinate.
So again, the 80 pops up, and it uses the value of
3 which is in the stationary frame, the only one
we are concerned with.
Do you believe that vt and ut + L are values in the
stationary frame? Do you believe the equation
vt = ut + L?
Well, of course, ducky.
Do you understand that all of the following are the
same equation? That if one of them is a relationship
between things in the stationary frame, then all of them
are?
vt = ut + L
v = u + L/t
vt - ut = L
OOPS! You've just used the Galilean transform and converted
to moving frame coordinates. You subtracted ut.
I started with this equation, which is in the ground
frame, relating things in the ground frame:
vt = ut + L
Since this is true in the ground frame, anything I
do to both sides is still true in the ground frame.
For instance, this:
vt - 10 = ut + L - 10
or this:
vt - L = ut + L - L
or this:
vt - vt = ut + L - vt
or this:
vt - at^2 + bt + c = ut + L - at^2 + bt + c
or this:
vt - ut = ut + L - ut
Why don't you show me how you came up with the
distance of 80 ft, and the time of 16 sec. I can't
see any way to get there without manipulating an
equation this way.
- Randy
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 10:13:14 AM |
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"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105366428.577772.171750@c13g2000cwb.googlegroups.com...
Androcles wrote:
The equation on the left hand
side shows "vt", which contains v and which has the value
of "80" for these numbers.
Correct.
The right hand side of this equation is "ut + L".
Correct, so it too has the value 80.
That
expresses in the stationary frame that after time t,
the walker has advanced a distance ut,
Correct, that is 48 ft.
How did you arrive at these numbers?
The Galilean Transform, of course.
L = x-ut.
Did you not
solve for t at some point? What did the process of
solving for t look like?
I used the Galilean Transform to give one distance and
two velocities, and because I happen to know time doesn't
change between frames (it is invariant),
I got the same answer as you, and did it the same way as you.
You, on the other hand seem to think the speed of light is
invariant and time is not, but are prepared to use the Galilean
Transform (without even realizing it) to arrive at the correct
solution. Then you want to play a silly game of one-up-man-ship
and make stupid remarks about my ability to understand
algebra. You started out by calling me idiotic, but now the tables
are turned. You are the idiot. You used invariant time.
I'll ask you again.
Is the speed of light invariant or is time invariant?
because he is
moving at velocity u, plus the distance L that he was
originally located.
Correct, and L +48 = 80.
You are still doing well, staying in the ground frame.
OK, so you agree that vt = ut + L is an equation
in the ground frame.
Yes.
The value of t that solves it
is the solution to this equation in the ground frame,
right?
Yes, if and only if time is invariant.
What is that solution?
Time is invariant.
Thus, at time t, the walker is at
position ut + L.
Very good. Jo is at coordinate x = 80 in the ground frame.
I knew you could do it.
Since it turns out that t is 16, then
this expression give 3*16 + 32 = 80.
Excellent. You've found the ground frame coordinate.
So again, the 80 pops up, and it uses the value of
3 which is in the stationary frame, the only one
we are concerned with.
Do you believe that vt and ut + L are values in the
stationary frame? Do you believe the equation
vt = ut + L?
Well, of course, ducky.
Do you understand that all of the following are the
same equation? That if one of them is a relationship
between things in the stationary frame, then all of them
are?
vt = ut + L
v = u + L/t
vt - ut = L
OOPS! You've just used the Galilean transform and converted
to moving frame coordinates. You subtracted ut.
I started with this equation, which is in the ground
frame, relating things in the ground frame:
vt = ut + L
Since this is true in the ground frame, anything I
do to both sides is still true in the ground frame.
For instance, this:
vt - 10 = ut + L - 10
or this:
vt - L = ut + L - L
or this:
vt - vt = ut + L - vt
or this:
vt - at^2 + bt + c = ut + L - at^2 + bt + c
or this:
vt - ut = ut + L - ut
Why don't you show me how you came up with the
distance of 80 ft, and the time of 16 sec. I can't
see any way to get there without manipulating an
equation this way.
Well, isn't it obvious? Time is invariant.
20 seconds round trip in the moving frame and
20 seconds round trip in the ground frame.
Since we both agree, I'd like to know why you still think
the speed of light is invariant and time is not (aside from
being idiotic, that is).
Androcles.
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 10:31:13 AM |
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Androcles says...
"Randy Poe" <poespam-trap@yahoo.com> wrote
Did you not
solve for t at some point? What did the process of
solving for t look like?
I used the Galilean Transform to give one distance and
two velocities
Okay, so you actually believe that it is impossible
to solve the equation
u t = v t + L
for t in terms of u,v and L without using the Galilean
transform?
--
Daryl McCullough
Ithaca, NY
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 12:44:36 PM |
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"Daryl McCullough" <daryl@atc-nycorp.com> wrote in message
news:cruakh0km4@drn.newsguy.com...
Androcles says...
"Randy Poe" <poespam-trap@yahoo.com> wrote
Did you not
solve for t at some point? What did the process of
solving for t look like?
I used the Galilean Transform to give one distance and
two velocities
Okay, so you actually believe that it is impossible
to solve the equation
u t = v t + L
for t in terms of u,v and L without using the Galilean
transform?
Of course not. Time is invariant, so go ahead and solve
ot using simple algebra. I'm not the one claiming c
is invariant and time isn't, you are. It's just algebra, after all.
Make up your mind.
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 01:31:56 PM |
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Androcles says...
"Daryl McCullough" <daryl@atc-nycorp.com> wrote
Okay, so you actually believe that it is impossible
to solve the equation
u t = v t + L
for t in terms of u,v and L without using the Galilean
transform?
Of course not. Time is invariant, so go ahead and solve
it using simple algebra.
Once again, whether or not time is invariant is *irrelevant*
to this problem. Whether the Galilean transform is correct
or not is irrelevant to this problem. What is relevant is
that in the ground frame, we have
u t = v t + L
It follows that in the ground frame
t = L/(u-v)
It is not necessary to assume anything about how time,
length, or velocities transform. Those issues are just irrelevant.
--
Daryl McCullough
Ithaca, NY
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| User: "Daryl McCullough" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 01:20:29 PM |
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Androcles says...
"Daryl McCullough" <daryl@atc-nycorp.com> wrote
Okay, so you actually believe that it is impossible
to solve the equation
u t = v t + L
for t in terms of u,v and L without using the Galilean
transform?
Of course not.
Well, it seemed like you were saying the opposite. So
we solve that for t, and we get
t = L/(u-v)
for travel from Sam to Joe, and similarly we get
t = L/(u+v)
for travel from Joe back to Sam. It is not necessary
to do a Galilean transform, all quantities are measured
in the *ground* frame, and no mention is made of any
measurements in Sam's frame or the frame of the mosquito.
Time is invariant, so go ahead and solve
it using simple algebra.
Whether or not time is invariant has nothing to do with
this particular problem. The question only involved measurements
in the ground frame.
--
Daryl McCullough
Ithaca, NY
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| User: "Randy Poe" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 12:54:28 PM |
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Androcles wrote:
Okay, so you actually believe that it is impossible
to solve the equation
u t = v t + L
for t in terms of u,v and L without using the Galilean
transform?
Of course not. Time is invariant, so go ahead and solve
ot using simple algebra. I'm not the one claiming c
is invariant and time isn't, you are. It's just algebra, after all.
Make up your mind.
Here's a new problem for you.
I am running a small business. I took out a loan of
L to start it. I have a nice steady income of u per
unit time. That is, my assets as a function of time
are ut.
Unfortunately, I also have costs, which over time amount
to a liability of vt. Including my loan, my total liability
is vt + L.
How long till I break even, i.e. my assets equal my
liabilities?
Solution: Set ut = vt + L
ut - vt = L
ACHTUNG! According to Androcles I just performed a
Galilean Transformation. Would he care to explain
what frame I just transformed to when I did this
"Galilean Transformation"?
- Randy
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| User: "Androcles" |
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| Title: Re: Androcles' long-winded solution to the mosquito problem |
10 Jan 2005 01:35:54 PM |
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"Randy Poe" <poespam-trap@yahoo.com> wrote in message
news:1105383268.064810.186360@c13g2000cwb.googlegroups.com...
Androcles wrote:
Okay, so you actually believe that it is impossible
to solve the equation
u t = v t + L
for t in terms of u,v and L without using the Galilean
transform?
Of course not. Time is invariant, so go ahead and solve
ot using simple algebra. I'm not the one claiming c
is invariant and time isn't, you are. It's just algebra, after all.
Make up your mind.
Here's a new problem for you.
Two ships are at sea, ok? There is no ground, the ships are
identical, and facing opposite directions. You are on one,
McCullough is on the other. Both ships have silent engines.
Neither of you can see land, you are way, way out in the ocean.
All you can see is water, your ship and the other ship.
The ships are passing at 3 fps.
You see McCullough take a leisurely stroll from the stern
(blunt end) to the bow (pointed end) of his ship,
__________________________
| \
| \
| /
|M_________________________/
as you are taking a similar stroll from the bow to the stern of your
ship.
__________________________
/P |
/ |
\ |
\__________________________|
You notice McCullough is trying to talk to you, but to keep up
with him, you have to break into a run.
McCullough walks the length of his ship, 320 ft, in 200 seconds.
How fast does McCullough say he is walking?
How fast are you running?
WHY are you running?
In 40 seconds you've reached the stern of your ship, also 320
ft long, and panting from your exertion, you see a deck chair
and sit in it. With 160 seconds still to go,
McCullough hasn't finished telling you what an idiot
Androcles is, so he reverses direction. Trouble is,
he can't sit down and you can. Why?
Eventually McCullough reaches the stern of his ship,
you are still at the stern of your ship, and you wave goodbye
to each other. How long did the conversation last?
Now for the really hard part (you are not going to get this)
One of the ships had its engine turned off.
Which ship had its engines turned off?
a) Poe's ship.
b) McCullough's ship.
When you can answer that question correctly, I'll explain
where I've posted the answer (so that there is no cheating, it
is timed and dated) and already sent prior to me posting this.
Androcles
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