let us place a block on a rigid horizontal plane. let the block slide along
this plane. we then observe that it gradually slows down and stops when the
hand initially pushing the block is removed. now using a smoother block and
a smoother plane and providing a lubricant, we note that the velocity
decreases more slowly than before. let us now use an air track and observe
that by tapping the glider, it moves at a slow and almost constant speed.
you can see that if all friction could be eliminated, the body would
continue indefinitely in a straight line with constant speed. an external
force then is needed to set the body in motion, but no external force is
needed to keep a body moving with constant velocity.

it is difficulty to find a situation in which no external force acts on a
body, we do not need to go to the vacuum of distant space to study motion
free of external force because there is no distinction between a body on
which no external force acts and a body on which the sum or resultant of all
the external forces (net force) is zero.

therefore, consider a body on which no net force acts. if the body is at
rest, it will remain at rest. if the body is moving with constant velocity,
it will continue to do so.

Francisco, I have posted my model's explanation of Newt's 1st law and
claimed that what you say above is just parrot talk from the science
community on these sci. ngs.

What you describe is fine, but your conclusion that no force is needed
for a discrete object to move on its own does not pass logical rules.
It can be that the object has an inherent force as Aristotle believed
and Newton claimed in his 1st law. Just because you don't see a force
moving the object does not mean there is no force necessary for it to
move.

External forces accelerate objects, but objects must have a force which
keeps them moving as described by Newt's 1st.

TomGee:

External forces accelerate objects, but objects must have a force which
keeps them moving as described by Newt's 1st.

GeeTom, if I launch a rocket which reaches escape velocity and
after leaving the atmosphere, I turn off the engines, how far will
the rocket ``coast'' before it ``stops?'' After it ``stops,'' what
will happen? Does it just sit there so that we here on earth pass
by it every year or are you assuming the earth is the center of the
universe so that the rocket just sits there at some fixed distance,
forever? Or, do you think it falls back to earth (which sort of makes
the term escape velocity a major misnomer)? Hurry up and send your
corrections to halliday & resnick before another generation has
been bullied into falling for newton's charade.

TERRORIST ALERT!!! This village idiot sends your replies to
alt.local.village.idiot!


Bilge wrote:
TomGee:

External forces accelerate objects, but objects must have a force which
keeps them moving as described by Newt's 1st.

GeeTom, if I launch a rocket which reaches escape velocity and
after leaving the atmosphere, I turn off the engines, how far will
the rocket ``coast'' before it ``stops?'' After it ``stops,'' what
will happen? Does it just sit there so that we here on earth pass
by it every year or are you assuming the earth is the center of the
universe so that the rocket just sits there at some fixed distance,
forever? Or, do you think it falls back to earth (which sort of makes
the term escape velocity a major misnomer)? Hurry up and send your
corrections to halliday & resnick before another generation has
been bullied into falling for newton's charade.

Well, Mr. Idiot Terrorist Bilge, AFAIK, Newton did not say how far nor for how long it would go. Another miscomprehension on your part, no? Wrote all that nonsense without understanding what I said. Tsk! Tsk! tsk! What a maroon!

TomGee:

TERRORIST ALERT!!! This village idiot sends your replies to
alt.local.village.idiot!

Stop being an idiotic terrorist and I'll consider setting followups
to a newsgroup that more closely coincides with whatever your new
incarnation of cluelessness suggests.


External forces accelerate objects, but objects must have a force which
keeps them moving as described by Newt's 1st.

GeeTom, if I launch a rocket which reaches escape velocity and
after leaving the atmosphere, I turn off the engines, how far will
the rocket ``coast'' before it ``stops?'' After it ``stops,'' what
will happen? Does it just sit there so that we here on earth pass
by it every year or are you assuming the earth is the center of the
universe so that the rocket just sits there at some fixed distance,
forever? Or, do you think it falls back to earth (which sort of makes
the term escape velocity a major misnomer)? Hurry up and send your
corrections to halliday & resnick before another generation has
been bullied into falling for newton's charade.

Well, Mr. Idiot Terrorist Bilge,

By Idiot Terrorist, do you mean anyone who doesn't follow your orders
about what he/she can and can't write in his/her own posts?

AFAIK, Newton did not say how far nor for how long it would go.

I guess that you don't know too much, then. Of course newton
said how far it would go. By definition, anything that reaches
escape velocity will keep going forever. Where did you encounter
the word physics such that you got the impression you knew something
about it?

Another miscomprehension on your part, no?

No. Of course not. You might want to see if you can understand
newton's laws before you start offering solutions to any outstanding
problems in physics. Of course, if you think that might take longer
than you could possibly live, you might prefer to just speculate and
get used to the derision.

Wrote all that nonsense without understanding what I said.
Tsk! Tsk! tsk! What a maroon!

Why did you write all that nonsense without understanding what you said?
Wouldn't you have been better off writing something you could understand?

TomGee wrote:
TERRORIST ALERT!!! This village idiot sends your replies to
alt.local.village.idiot!


Bilge wrote:
TomGee:

External forces accelerate objects, but objects must have a force which
keeps them moving as described by Newt's 1st.

GeeTom, if I launch a rocket which reaches escape velocity and
after leaving the atmosphere, I turn off the engines, how far will
the rocket ``coast'' before it ``stops?'' After it ``stops,'' what
will happen? Does it just sit there so that we here on earth pass
by it every year or are you assuming the earth is the center of the
universe so that the rocket just sits there at some fixed distance,
forever? Or, do you think it falls back to earth (which sort of makes
the term escape velocity a major misnomer)? Hurry up and send your
corrections to halliday & resnick before another generation has
been bullied into falling for newton's charade.


Well, Mr. Idiot Terrorist Bilge, AFAIK, Newton did not say how far nor for how long it would go. Another
miscomprehension on your part, no? Wrote all that nonsense without understanding what I said. Tsk! Tsk! tsk!
What a maroon!

On the contrary, Newton accepted what Galileo had to say in the matter,
and Galileo was quite explicit about what happens to objects without
any net external force being impressed upon them. However, you haven't
found any of Galileo's writings condensed to 12 lines on the web for
your benefit, and you won't go to the library to read, so it's not much
of a surprise.

PD

More personal opinions, eh, PD? Wild claims with no support. Carry
on....

TomGee:
More personal opinions, eh, PD? Wild claims with no support. Carry
on....

On the contrary, newtonian mechanics has a great deal of support.

TERRORIST ALERT!!! This moron sends your replies to alt.moron.


Bilge wrote:
TomGee:
More personal opinions, eh, PD? Wild claims with no support. Carry
on....

On the contrary, newtonian mechanics has a great deal of support.


The fact that you're a moron gives your opinions a great deal of
support.

TomGee wrote:
TERRORIST ALERT!!! This moron sends your replies to alt.moron.


Bilge wrote:
TomGee:
More personal opinions, eh, PD? Wild claims with no support. Carry
on....

On the contrary, newtonian mechanics has a great deal of support.


The fact that you're a moron gives your opinions a great deal of
support.

You know, for someone who objects to teachers making students feel
stupid, you sure are free with terms like "moron". Bilge made a
statement of fact, without any judgement placed on you personally at
all, and you respond by calling him "moron". Would it be fair to call
this hypocritical behavior?

PD