| Topic: |
Religions > Atheism |
| User: |
"Maverick" |
| Date: |
17 Apr 2004 11:29:15 AM |
| Object: |
Another test: Basic Physics Savvy Quiz |
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
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| User: "Mike Painter" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
17 Apr 2004 12:26:12 PM |
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"Maverick" <insensitive_clod@hotmail.com> wrote in message
news:Xns94CEBBF4CE479insensitiveclodhotma@192.71.180.100...
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
The web site says this could be used as a pre or post test for a basic
physics class.
There are no questions that measure a knowledge of physics.
I know Boyles law and I know PV = nrT but I can never remember which is
Charles law.
Asking me to solve a problem involving V and T is a physics test. Asking me
a name is not.
This might be nice if it was for a history of physics class but is about as
valid a measure of a knowledge of physics as a quiz about your name, your
favorite color, your quest, and how much a sparrow weighs.
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| User: "raven1" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
17 Apr 2004 01:57:04 PM |
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On Sat, 17 Apr 2004 17:26:12 GMT, "Mike Painter" <mdotpainter@att.net>
wrote:
"Maverick" <insensitive_clod@hotmail.com> wrote in message
news:Xns94CEBBF4CE479insensitiveclodhotma@192.71.180.100...
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
The web site says this could be used as a pre or post test for a basic
physics class.
There are no questions that measure a knowledge of physics.
I know Boyles law and I know PV = nrT but I can never remember which is
Charles law.
Asking me to solve a problem involving V and T is a physics test. Asking me
a name is not.
This might be nice if it was for a history of physics class but is about as
valid a measure of a knowledge of physics as a quiz about your name, your
favorite color, your quest, and how much a sparrow weighs.
That's just a pop quiz on the cultural impact of physics on the
introductory page. Here's the actual test:
http://www.intuitor.com/physics_test/PhysicsSavvy.html
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| User: "Sverker Johansson" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
19 Apr 2004 02:25:48 AM |
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Maverick <insensitive_clod@hotmail.com> wrote in message news:<Xns94CEBBF4CE479insensitiveclodhotma@192.71.180.100>...
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
100%.
I quickly recognized what the test was trying to do,
and that got me past the occasional ambiguity.
The test is designed to address a lot of common
misconceptions about physics, as well as cases where
the everyday meaning of a word is different from
the physical concept (such as acceleration).
Best regards,
Sverker Johansson
-----------------------------
"A man's ethical behavior should be based effectually on sympathy,
education, and social ties; no religious basis is necessary. Man would
indeed be in a poor way if he had to be restrained by fear of
punishment and hope of reward after death." - Albert Einstein
------------------------------
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| User: "Andrew Lias" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
20 Apr 2004 04:41:02 PM |
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Maverick <insensitive_clod@hotmail.com> wrote in message news:<Xns94CEBBF4CE479insensitiveclodhotma@192.71.180.100>...
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
I got 90%. I suspected that three of the one's I missed were wrong
when I submitted the answers, but I got confused by the terminology.
The fourth one I missed, which was regarding the direction a current
travels in a circuit, was something I genuinely didn't know.
Fun all around.
--
Andrew Lias
http://andrewlias.blogspot.com
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| User: "bluskie" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
17 Apr 2004 06:10:18 PM |
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Maverick <insensitive_clod@hotmail.com> wrote in message news:<Xns94CEBBF4CE479insensitiveclodhotma@192.71.180.100>...
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
does that mean you are now qualified to build a nuclear device? better
be careful dubya doesnt try to bomb your home looking for weapons of
mass destuction.
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| User: "Olrik" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
17 Apr 2004 10:45:45 PM |
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Maverick wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
72.5
As others said, a few questions were a bit loaded or imprecise.
--
Olrik
aa #1981
Qualified SMASH member
EAC Chief Food Inspector, Bacon Division
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| User: "Maverick" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 12:35:51 AM |
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Olrik <olrik666@yahoo_BACON!_.com> wrote in news:JRmgc.47594$S%4.1854886
@wagner.videotron.net:
Maverick wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
72.5
As others said, a few questions were a bit loaded or imprecise.
Which ones, in your opinion?
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| User: "Olrik" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 02:28:45 AM |
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Maverick wrote:
Olrik <olrik666@yahoo_BACON!_.com> wrote in news:JRmgc.47594$S%4.1854886
@wagner.videotron.net:
Maverick wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
72.5
As others said, a few questions were a bit loaded or imprecise.
Which ones, in your opinion?
15) When an object has negative acceleration, the object has to be
slowing down.
I never heard of "negative acceleration" before. I thought it was
decellaration.
23) Friction provides the force which "pushes" a car forward as it
drives down the road.
"Pushes"?
You don't need quotes when asking physics questions. I got that one
because I knew that it was the right answer, but the word "pushes" is
loaded.
--
Olrik
aa #1981
Qualified SMASH member
EAC Chief Food Inspector, Bacon Division
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| User: "Maverick" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 04:25:39 AM |
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Olrik <olrik666@yahoo_BACON!_.com> wrote in news:N6qgc.1508$Ju.1858
@weber.videotron.net:
Maverick wrote:
Olrik <olrik666@yahoo_BACON!_.com> wrote in news:JRmgc.47594$S%4.1854886
@wagner.videotron.net:
Maverick wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
72.5
As others said, a few questions were a bit loaded or imprecise.
Which ones, in your opinion?
15) When an object has negative acceleration, the object has to be
slowing down.
I never heard of "negative acceleration" before. I thought it was
decellaration.
I've both heard it and seen it pretty much everywhere. Perhaps it depends
on what books you read, what teachers you've had and what physics websites
you visit.
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| User: "Kronk" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 03:53:59 AM |
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On Sun, 18 Apr 2004 05:35:51 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Olrik <olrik666@yahoo_BACON!_.com> wrote in news:JRmgc.47594$S%4.1854886
@wagner.videotron.net:
Maverick wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
72.5
As others said, a few questions were a bit loaded or imprecise.
Which ones, in your opinion?
eg.
23) Friction provides the force which "pushes" a car forward as it
drives down the road.
a) "The" force implies the exclusion of others, and a sloped road can
impart a forward force without friction.
b) There are times when the pavement provides a force which pushes the
car rearward or sideward as it drives down the road.
c) There are some tire engineers who distinguish surface friction from
road surface interlinkage due to tire deformation. Unless we would
like to classify a gear linkage as a friction linkage, I think there
is some merit to that view, in which case, friction would often
provide only part of the forward force, when forward force is being
provided.
----
17) Shanda drives around a circular track exactly 12 times in 2 hours.
Her speedometer constantly reads exactly 15 miles per hour during this
time. Her average velocity is zero for the trip.
a) This is really more of a physics vocabulary question than a
physical principles question. "The rate of speed of an action" is a
perfectly valid English definition of 'velocity' (that meaning
actually preceded the physics meaning).
b) The question does not specify a stationary circular track (wherever
you would find one of those) or simply specify that she ended up
exactly at her start point.
----
15) When an object has negative acceleration, the object has to be
slowing down.
I'm going to take the position that "negative acceleration" is a
nonsensical, or at the very least, sloppy term--at least until someone
shows why it is not.
----
12) Susan jumps off a chair. As she is falling, the Earth’s
gravitational force on her is higher than her gravitational force on
the Earth.
13) An astronaut orbits the Earth 500 miles above its surface. She
appears to be weightless because there is virtually no gravitational
force on her.
Both of these assume gravity acts as a force on weightless bodies.
Einstein would not have agreed. These might have been better in the
Newton section.
----
24) If a car hits a tree, the car’s occupants (assume no seat belts or
air bags) will be violently thrown forward due to a force created by
the car seats.
That account is a pretty fair description of what would happen if a
car hits a tree while traveling in reverse. It isn't an exact
description, but it is certainly within the slop tolerance of this
quiz.
----
30) An atom is like a tiny solar system in which the nucleus is like
the Sun and electrons are like tiny planets orbiting the nucleus.
"Like" is a vague term.
----
38) A milliliter is exactly the same size as a cubic centimeter.
"Size" isn't a physics term, and a common English meaning of size is
"the physical dimensions and proportions of an object". A milliliter
could have very different dimensions and proportions from a cubic
centimeter.
Kronk
(I also dissent from the explanations given on questions 6 and 39.)
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| User: "Maverick" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 04:21:27 AM |
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(Kronk) wrote in news:408220e8.52859387@news.gvtc.com:
On Sun, 18 Apr 2004 05:35:51 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Olrik <olrik666@yahoo_BACON!_.com> wrote in news:JRmgc.47594$S%
4.1854886
@wagner.videotron.net:
Maverick wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
72.5
As others said, a few questions were a bit loaded or imprecise.
Which ones, in your opinion?
eg.
23) Friction provides the force which "pushes" a car forward as it
drives down the road.
a) "The" force implies the exclusion of others, and a sloped road can
impart a forward force without friction.
Sure, but I don't think it would be too far off to assume that the
conditions are the simplest possible.
b) There are times when the pavement provides a force which pushes the
car rearward or sideward as it drives down the road.
They should of course state that there is absolutely no other force
working on the car at all...
c) There are some tire engineers who distinguish surface friction from
road surface interlinkage due to tire deformation. Unless we would
like to classify a gear linkage as a friction linkage, I think there
is some merit to that view, in which case, friction would often
provide only part of the forward force, when forward force is being
provided.
----
17) Shanda drives around a circular track exactly 12 times in 2 hours.
Her speedometer constantly reads exactly 15 miles per hour during this
time. Her average velocity is zero for the trip.
a) This is really more of a physics vocabulary question than a
physical principles question. "The rate of speed of an action" is a
perfectly valid English definition of 'velocity' (that meaning
actually preceded the physics meaning).
Ok, so the question should've been more clear that it is velocity and not
speed? I thought that was what it said too. It wasn't a question on what
the word velocity meant.
b) The question does not specify a stationary circular track (wherever
you would find one of those) or simply specify that she ended up
exactly at her start point.
I think it's fair to assume that it was a way to describe a perfectly
circular motion... otherwise they would say that it wasn't exactly
circular and she didn't end up at the exact starting point, and give
information on that, too.
----
15) When an object has negative acceleration, the object has to be
slowing down.
I'm going to take the position that "negative acceleration" is a
nonsensical, or at the very least, sloppy term--at least until someone
shows why it is not.
I have never heard, anywhere, that the term "negative acceleration" would
be wrong in any way... I thought that it was a common term.
----
12) Susan jumps off a chair. As she is falling, the Earth’s
gravitational force on her is higher than her gravitational force on
the Earth.
13) An astronaut orbits the Earth 500 miles above its surface. She
appears to be weightless because there is virtually no gravitational
force on her.
Both of these assume gravity acts as a force on weightless bodies.
Einstein would not have agreed. These might have been better in the
Newton section.
I agree with you on this one.
----
24) If a car hits a tree, the car’s occupants (assume no seat belts or
air bags) will be violently thrown forward due to a force created by
the car seats.
That account is a pretty fair description of what would happen if a
car hits a tree while traveling in reverse. It isn't an exact
description, but it is certainly within the slop tolerance of this
quiz.
I simply assumed that the car was going forward, but yes you're right.
----
30) An atom is like a tiny solar system in which the nucleus is like
the Sun and electrons are like tiny planets orbiting the nucleus.
"Like" is a vague term.
Would you say that based on what we know, the atom and the solar system
are comparable? I wouldn't.
----
38) A milliliter is exactly the same size as a cubic centimeter.
"Size" isn't a physics term, and a common English meaning of size is
"the physical dimensions and proportions of an object". A milliliter
could have very different dimensions and proportions from a cubic
centimeter.
Volume would have been a better term then.
Kronk
(I also dissent from the explanations given on questions 6 and 39.)
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| User: "Kronk" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 05:52:02 AM |
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On Sun, 18 Apr 2004 09:21:27 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
void@isp.com (Kronk) wrote in news:408220e8.52859387@news.gvtc.com:
On Sun, 18 Apr 2004 05:35:51 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Olrik <olrik666@yahoo_BACON!_.com> wrote in news:JRmgc.47594$S%
4.1854886
@wagner.videotron.net:
Maverick wrote:
<...>
As others said, a few questions were a bit loaded or imprecise.
Which ones, in your opinion?
eg.
23) Friction provides the force which "pushes" a car forward as it
drives down the road.
b) There are times when the pavement provides a force which pushes the
car rearward or sideward as it drives down the road.
They should of course state that there is absolutely no other force
working on the car at all...
Well, by the way they use terms, if no other force is working on the
car, then no forward force is needed to push it forward as it drives
down the road. Forward acceleration would be the only time forward
force would be applied (and that type of acceleration is not
especially more typical of driving than rearward or sideward
acceleration).
----
17) Shanda drives around a circular track exactly 12 times in 2 hours.
Her speedometer constantly reads exactly 15 miles per hour during this
time. Her average velocity is zero for the trip.
a) This is really more of a physics vocabulary question than a
physical principles question. "The rate of speed of an action" is a
perfectly valid English definition of 'velocity' (that meaning
actually preceded the physics meaning).
Ok, so the question should've been more clear that it is velocity and not
speed?
It would have helpful to clarify that it was using the physics meaning
of velocity, and not the original and commonplace meaning.
b) The question does not specify a stationary circular track (wherever
you would find one of those) or simply specify that she ended up
exactly at her start point.
I think it's fair to assume that it was a way to describe a perfectly
circular motion... otherwise they would say that it wasn't exactly
circular
A perfectly circular track can still move over time, like when it is
on a rotating and orbiting planet for example. And there was no need
to specify a circular track at all. It could have been most any
closed shape if the only point of the track was to get her back to her
original position. And the clearest and simplest way to specify that
is to simply say she arrived back exactly at her start position.
----
15) When an object has negative acceleration, the object has to be
slowing down.
I'm going to take the position that "negative acceleration" is a
nonsensical, or at the very least, sloppy term--at least until someone
shows why it is not.
I have never heard, anywhere, that the term "negative acceleration" would
be wrong in any way... I thought that it was a common term.
The common term for that would be deceleration, but physicists don't
use that term because they take the position that acceleration is
acceleration, no matter in which direction. It would be silly to shun
the common word deceleration and then turn right around and embrace
the term 'negative acceleration' for occasions when the acceleration
happens to be in an arbitrarily assigned negative direction.
And the notion of a negative direction really only makes sense in
one dimension. Motion on a cartesian plane might have an acceleration
vector which resolves into a negative direction along the x axis and a
positive direction along the y. So that would be negative-positive
acceleration? And presumably, that would be something distinct from
positive-negative acceleration. And how about something traveling in
a perfect circle at a steady rate of speed? Should we describe it as
experiencing constant acceleration, or should we say it is
experiencing a succession of positive-positive, positive-negative,
negative-negative, and negative-positive accelerations? And that's
still just in two dimensions.
----
30) An atom is like a tiny solar system in which the nucleus is like
the Sun and electrons are like tiny planets orbiting the nucleus.
"Like" is a vague term.
Would you say that based on what we know, the atom and the solar system
are comparable? I wouldn't.
They are comparable in that they can be compared. I would say the
differences are much greater than the similarities--but I would have
said the same thing back when physicists themselves were comparing the
atom to a solar system.
38) A milliliter is exactly the same size as a cubic centimeter.
<...>
Volume would have been a better term then.
Indeed.
Kronk
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| User: "Mark Richardson" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 08:34:15 PM |
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On Sun, 18 Apr 2004 09:21:27 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
----
30) An atom is like a tiny solar system in which the nucleus is like
the Sun and electrons are like tiny planets orbiting the nucleus.
"Like" is a vague term.
Would you say that based on what we know, the atom and the solar system
are comparable? I wouldn't.
That wasn't what the question asked.
The mass of the Solar system is concentrated in the Sun.
The mass of the atom is concentrated in the nucleus.
So they are alike in that aspect - so they are alike.
The Sun is like the nucleus and the planets are like the electrons.
The planets have angular momentum about the sun.
The electrons have angular momentum about the nucleus.
So they are alike in that aspect - so they are alike.
Are they unalike in certain other aspects?
Sure.
Is a bacteria like an elephant?
Sure they are both made of the same kinds of carbon molecules - DNA
protien ...
They both respire.
etc etc.
Are they unalike in certain ways?
Sure.
Mark.
--
Mark Richardson mDOTrichardsonATutasDOTeduDOTau
"My name is Mark I am a recovering Skeptic
(AKA Muddy Boggs, AKA Donald R. Alford AKA ...)
debater. It is 026 days since I last tried to argue
with him."
You too can quit! Take the pledge!
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| User: "SMChristenson" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 10:08:37 AM |
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On Sat, 17 Apr 2004 16:29:15 +0000, Maverick wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
90% here. One of the "common misperceptions" in particular got me. I
thought it was pretty fair. Physics is rocket science, after all.
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| User: "Mark Richardson" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 08:19:23 PM |
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On Sat, 17 Apr 2004 16:29:15 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
I got 90% - i.e. 4 "wrong" answers.
If I could have answered something other than "true or false" I feel
certain I would have got 100%.
(assuming competency in the marker)
I can say this because on reading the explanation i thought "Sure I
knew that".
Consider:
3) When touching an object, the sensation of hot and cold is a measure
of object's overall temperature.
True False
The required answer is "false" - but that is misleading because
although the sensation of heat cold is imperfect it is nonetheless "a"
measure of a bodies temperature.
All measurements - whether made by your pinky finger or a $20,000
piece of high tech electronics need to be interpreted intelligently.
The other answer "true" is also misleading because
(a) the sensation of hot/cold will give you a measure of the
temperature of the surface of the body and not *necessarily* the whole
body (but if its a sphere of copper that has been in a precision
controlled oven for two hours - then the sensation of hot or cold
will be an excellent indicator of the bodies temperature!) - In other
words "it depends".
(b) the sensation of hot/cold gives a measure of *relative*
temperature - if your hand has been in a ice water bath for 2 minutes
then objects at room temperature will feel hot - if you hand has been
in a hot water bath for 2 minutes then objects at room temperature
will feel cold. In any case the sensation of hot cold is giving a
measure a bodies temperature - its just giving an inaccurate and
relative one.
Some of the other questions are similarly dubious as "true/false"
questions.
Is the atom "like" a minature solar system?
Well - Yes and No.
Is it more unalike than like?
Yes - but that wasnt the question asked.
Mark.
--
Mark Richardson mDOTrichardsonATutasDOTeduDOTau
"My name is Mark I am a recovering Skeptic
(AKA Muddy Boggs, AKA Donald R. Alford AKA ...)
debater. It is 026 days since I last tried to argue
with him."
You too can quit! Take the pledge!
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| User: "Kronk" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
17 Apr 2004 04:13:17 PM |
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On Sat, 17 Apr 2004 16:29:15 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
I got 80%.
The correct answer for some of the questions is "depends". Where I
could imagine scanarios where the answer would be false, I put false
and it scored a couple of those wrong.
K.
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| User: "Kronk" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
17 Apr 2004 04:24:44 PM |
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On Sat, 17 Apr 2004 16:29:15 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
Oh yeah, I'm curious how an object can have negative acceleration.
K.
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| User: "Colin Day" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
17 Apr 2004 09:10:28 PM |
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Kronk wrote:
On Sat, 17 Apr 2004 16:29:15 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
Oh yeah, I'm curious how an object can have negative acceleration.
Acceleration in the negative direction. When you toss a baseball
into the air, its downward acceleration can be viewed as negative.
Colin Day aa #1500
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| User: "Kronk" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
17 Apr 2004 10:49:24 PM |
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On Sun, 18 Apr 2004 02:10:28 GMT, Colin Day <cday3@sc.rr.com> wrote:
Kronk wrote:
On Sat, 17 Apr 2004 16:29:15 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
Oh yeah, I'm curious how an object can have negative acceleration.
Acceleration in the negative direction. When you toss a baseball
into the air, its downward acceleration can be viewed as negative.
And then the negative acceleration becomes positive acceleration as
soon as the ball starts descending? Isn't the ball experiencing the
same acceleration whether it is rising or descending?
K.
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| User: "Colin Day" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 10:14:30 AM |
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Kronk wrote:
On Sun, 18 Apr 2004 02:10:28 GMT, Colin Day <cday3@sc.rr.com> wrote:
Kronk wrote:
On Sat, 17 Apr 2004 16:29:15 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
Oh yeah, I'm curious how an object can have negative acceleration.
Acceleration in the negative direction. When you toss a baseball
into the air, its downward acceleration can be viewed as negative.
And then the negative acceleration becomes positive acceleration as
soon as the ball starts descending? Isn't the ball experiencing the
same acceleration whether it is rising or descending?
Whether the acceleration is positive or negative depends on how
the coordinates are set up. If one treats up as vertically positive,
then the ball's acceleration is negative.
Colin Day aa #1500
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| User: "Kronk" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 12:35:11 PM |
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On Sun, 18 Apr 2004 15:14:30 GMT, Colin Day <cday3@sc.rr.com> wrote:
Kronk wrote:
On Sun, 18 Apr 2004 02:10:28 GMT, Colin Day <cday3@sc.rr.com> wrote:
Kronk wrote:
On Sat, 17 Apr 2004 16:29:15 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
Oh yeah, I'm curious how an object can have negative acceleration.
Acceleration in the negative direction. When you toss a baseball
into the air, its downward acceleration can be viewed as negative.
And then the negative acceleration becomes positive acceleration as
soon as the ball starts descending? Isn't the ball experiencing the
same acceleration whether it is rising or descending?
Whether the acceleration is positive or negative depends on how
the coordinates are set up. If one treats up as vertically positive,
then the ball's acceleration is negative.
If we were to call up acceleration positive acceleration, and down
acceleration negative acceleration, then presumably the 8 ball would
experience a zero acceleration when the cue ball strikes it.
Calling it negative acceleration gives the impression that it is the
very nature of acceleration itself which is inverted, and not that it
describes some relationship to an arbitrarily-assigned name for a
direction. I could go along with negative-wards acceleration, same as
I'd go along with blue-wards acceleration, but to describe the
acceleration as negative strikes me as at least as confusing as to
describe the acceleration as blue.
Kronk
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| User: "Enkidu" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 12:52:19 PM |
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In article <4082b5b2.426523@news.gvtc.com>, says...
Whether the acceleration is positive or negative depends on how
the coordinates are set up. If one treats up as vertically positive,
then the ball's acceleration is negative.
If we were to call up acceleration positive acceleration, and down
acceleration negative acceleration, then presumably the 8 ball would
experience a zero acceleration when the cue ball strikes it.
No. If the 8 ball goes from a velocity of zero m/s to a velocity of 0.1
m/s, and the time of contact is, say 0.01 seconds, then dv/dt is
(0.1m/s)/(0.01s) = 10m/s^2, averaged over the 0.01 seconds they are in
contact.
Calling it negative acceleration gives the impression that it is the
very nature of acceleration itself which is inverted, and not that it
describes some relationship to an arbitrarily-assigned name for a
direction. I could go along with negative-wards acceleration, same as
I'd go along with blue-wards acceleration, but to describe the
acceleration as negative strikes me as at least as confusing as to
describe the acceleration as blue.
Not at all. Acceleration is a vector quantity. The "negative" refers
only to the direction, and is arbitrary. If you assign ground level as
zero, and the height above ground in feet as positive, then the
acceleration of a batted ball in flight has a positive velocity until it
reached its highest point, then a negative velocity as it comes back
down. The acceleration due to gravity, though, is always negative in
this example because it down, the opposite of up, and that was defined
by the choice of reference frame.
--
Enkidu
AA# 2165
"Suppose we've chosen the wrong god. Every time we
go to church we're just making him madder and madder."
--Homer Simpson
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| User: "Kronk" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 04:33:53 PM |
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On Sun, 18 Apr 2004 10:52:19 -0700, Enkidu <enkidu@leaddogs.org>
wrote:
In article <4082b5b2.426523@news.gvtc.com>, says...
Whether the acceleration is positive or negative depends on how
the coordinates are set up. If one treats up as vertically positive,
then the ball's acceleration is negative.
If we were to call up acceleration positive acceleration, and down
acceleration negative acceleration, then presumably the 8 ball would
experience a zero acceleration when the cue ball strikes it.
No. If the 8 ball goes from a velocity of zero m/s to a velocity of 0.1
m/s, and the time of contact is, say 0.01 seconds, then dv/dt is
(0.1m/s)/(0.01s) = 10m/s^2, averaged over the 0.01 seconds they are in
contact.
That gives the magnitude of the zero acceleration, but that does not
argue against the label "zero acceleration" to describe acceleration
which is neither in the positive nor the negative direction.
...Acceleration is a vector quantity. The "negative" refers
only to the direction, and is arbitrary.
Since it is arbitrary, we could have a 3D coordinate system where X
and Z positive slope upwards diagonally, and Y positive slopes
downwards diagonally. So in that case, should we call vertical up
acceleration positive-negative-positive acceleration and vertical down
acceleration negative-positive-negative acceleration? If not, why
not?
Kronk
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| User: "Roy Sinnamond" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 04:51:39 PM |
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On Sun, 18 Apr 2004 21:33:53 +0000, Kronk wrote:
On Sun, 18 Apr 2004 10:52:19 -0700, Enkidu <enkidu@leaddogs.org>
wrote:
In article <4082b5b2.426523@news.gvtc.com>, says...
Whether the acceleration is positive or negative depends on how
the coordinates are set up. If one treats up as vertically positive,
then the ball's acceleration is negative.
If we were to call up acceleration positive acceleration, and down
acceleration negative acceleration, then presumably the 8 ball would
experience a zero acceleration when the cue ball strikes it.
No. If the 8 ball goes from a velocity of zero m/s to a velocity of 0.1
m/s, and the time of contact is, say 0.01 seconds, then dv/dt is
(0.1m/s)/(0.01s) = 10m/s^2, averaged over the 0.01 seconds they are in
contact.
That gives the magnitude of the zero acceleration, but that does not
argue against the label "zero acceleration" to describe acceleration
which is neither in the positive nor the negative direction.
...Acceleration is a vector quantity. The "negative" refers
only to the direction, and is arbitrary.
Since it is arbitrary, we could have a 3D coordinate system where X
and Z positive slope upwards diagonally, and Y positive slopes
downwards diagonally. So in that case, should we call vertical up
acceleration positive-negative-positive acceleration and vertical down
acceleration negative-positive-negative acceleration? If not, why
not?
Kronk
http://ocw.mit.edu/OcwWeb/Physics/8-01Physics-IFall1999/VideoLectures/index.htm
Lecture 2 in particular...
--
Roy Sinnamond
aa #1798 EAC Minister of Cognitive Dissonance
roysinnamond at mac dot com
"If you wish to make an apple pie from scratch, you must first invent the
universe."
-- Carl Sagan
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| User: "Mark Richardson" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 07:27:03 PM |
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On Sun, 18 Apr 2004 21:33:53 GMT, (Kronk) wrote:
On Sun, 18 Apr 2004 10:52:19 -0700, Enkidu <enkidu@leaddogs.org>
wrote:
In article <4082b5b2.426523@news.gvtc.com>, says...
Whether the acceleration is positive or negative depends on how
the coordinates are set up. If one treats up as vertically positive,
then the ball's acceleration is negative.
The above is the truth the whole truth and nothing but the truth.
8-)
If we were to call up acceleration positive acceleration, and down
acceleration negative acceleration, then presumably the 8 ball would
experience a zero acceleration when the cue ball strikes it.
It would experience 0 acceleration in the up or down direction.
No. If the 8 ball goes from a velocity of zero m/s to a velocity of 0.1
m/s, and the time of contact is, say 0.01 seconds, then dv/dt is
(0.1m/s)/(0.01s) = 10m/s^2, averaged over the 0.01 seconds they are in
contact.
That gives the magnitude of the zero acceleration, but that does not
argue against the label "zero acceleration" to describe acceleration
which is neither in the positive nor the negative direction.
...Acceleration is a vector quantity. The "negative" refers
only to the direction, and is arbitrary.
Since it is arbitrary, we could have a 3D coordinate system where X
and Z positive slope upwards diagonally, and Y positive slopes
downwards diagonally. So in that case, should we call vertical up
acceleration positive-negative-positive acceleration and vertical down
acceleration negative-positive-negative acceleration? If not, why
not?
Kronk
The terms negative and positive make sense in a one dimensional
coordinate system.
in general acceleration would be expressed as a 3-tuple vector.
in general a three tuple isnt positive or negative.
e.g. is (-4,0,4) ft/s/s - positive or negative?
It doent make sense to say either.
If the only dimension under consideration is "up -down" then the terms
negative and positive can be *assigned* a meaning.
What is "deceleration" and what is "acceleration" is entirely a matter
of choice.
Mark.
--
Mark Richardson mDOTrichardsonATutasDOTeduDOTau
"My name is Mark I am a recovering Skeptic
(AKA Muddy Boggs, AKA Donald R. Alford AKA ...)
debater. It is 026 days since I last tried to argue
with him."
You too can quit! Take the pledge!
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| User: "Colin Day" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 07:35:56 PM |
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Kronk wrote:
On Sun, 18 Apr 2004 15:14:30 GMT, Colin Day <cday3@sc.rr.com> wrote:
Whether the acceleration is positive or negative depends on how
the coordinates are set up. If one treats up as vertically positive,
then the ball's acceleration is negative.
If we were to call up acceleration positive acceleration, and down
acceleration negative acceleration, then presumably the 8 ball would
experience a zero acceleration when the cue ball strikes it.
Calling it negative acceleration gives the impression that it is the
very nature of acceleration itself which is inverted, and not that it
describes some relationship to an arbitrarily-assigned name for a
direction. I could go along with negative-wards acceleration, same as
I'd go along with blue-wards acceleration, but to describe the
acceleration as negative strikes me as at least as confusing as to
describe the acceleration as blue.
Others have responded, but I will also respond.
If one considers motion in three dimensions, then one
assigns a positive and negative direction in each
dimension.
Colin Day
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| User: "raven1" |
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| Title: Re: Another test: Basic Physics Savvy Quiz |
18 Apr 2004 03:09:00 AM |
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On Sat, 17 Apr 2004 21:24:44 GMT, (Kronk) wrote:
On Sat, 17 Apr 2004 16:29:15 GMT, Maverick
<insensitive_clod@hotmail.com> wrote:
Another test... "Basic Physics Savvy Quiz"
http://www.intuitor.com/physics_test/
Oh yeah, I'm curious how an object can have negative acceleration.
Step on the brakes while driving.
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