Science Project

podzol said:

Gilby's right: centrifugal force is a measurable phenomenon equal and
opposite to the centripetal force, that scientists use all the time
(centrifuges are an example).

Ofcourse, I forgot to mention that every action has an equal and
opposite reaction, the marble is pulling as hard on the string as the
string is pulling on the marble. This does not mean there is
centrifugal force. If there is no centripetal force, or when the
'centrifugal' force is equal to the centripetal force, the marble will
go in a straight line. This is what happens in a centrifuge, a
centrifuge has holes in it, so at that spot, there is no centripetal
force. No centripetal force means the object (water in this case, or
uranium hexfloride gas in another) will be pushed outwards, and
continue moving in the direction of the
velocity vector. If there was such a thing as centrifugal force, the
object would be moving in the direction of the place vector.

If I'm wrong, I'd love to know how an object can turn, when the forces
acting upon it are equal, and thus the acceleration. You can test this
with a string, and a knot in the middle. Move it over the table,
pulling equally hard on each side of the string, now, pull harder on
one side then the other. Result is that the knot will deviate from it's
path. Ofcourse, this is lateral movement, not radial, but the same
principle applies.

P.S

I might have made a few mistakes in the scientific terms, but English
is my second language.

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I think it is perfectly okay to say it is a force, knowing that it is
really a result of a number of factors that results in a force-like
effect. We could rewrite all the literature and say "centrifugal
effect" rather than centrifual force, but in any case, it is
-effectively -equal and opposite of the centripetal force and can even
be introduced into computations as such.

-Sensu strictu -, it is not a force. In forum-speak and in the spirit
of getting along, I find 'Yes, buts...' more amicable than 'No, you're
wrongs.'

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Maybe it would be less complicated to do a scientific behavioral study
on the effects of mentioning science and unicycle on a thread in a
public forum. It'd be much more interesting. 😉

--
Trapper
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podzol said:

I think it is perfectly okay to say it is a force, knowing that it is
really a result of a number of factors that results in a force-like
effect. We could rewrite all the literature and say "centrifugal
effect" rather than centrifual force, but in any case, it is
-effectively -equal and opposite of the centripetal force and can even
be introduced into computations as such.

-Sensu strictu -, it is not a force. In forum-speak and in the spirit
of getting along, I find 'Yes, buts...' more amicable than 'No, you're
wrongs.'

Sorry, I didn't mean to offend you. I do realize that in some systems,
mainly non-Newtonian (For example, accelerating systems) the
centrifugal force is used as a real force to attribute movement of
object, such as when you're making a turn with your car, and you're
using the car as a reference frame, things start sliding on your
dashboard.

I do however think that this matter might be slightly sophisticated for
a science project, especially if you start bringing it things like
inertia ( I = .5M((R1)^2+(R2)^2) for a hollow cylinder (like a wheel,
which is basically a short hollow cylinder), with R1 the distance from
the center to the inside of the wheel, and R2 the distance from the
center to the outside of the wheel, both in meters, and M the weight or
mass of the wheel. Ofcourse, you're neglecting the cranks here, which
would be I = (1/3)ML^2 with M the mass of one crank, and L the length
of one crank. (All formula's courtesy of Physics for Scientists and
Engineers by Paul A. Tipler))

I also think it amazing to find so many physicists (Or at least people
who know quite a bit about it) on a non-physics forum. Maybe that'd be
a good study, amount of people with high IQs on a unicycle 😉

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Erant said:

Maybe that'd be a good study, amount of people with high IQs on a
unicycle 😉

I used to think the same myself until the whole slew of "Sequel to Most
Replies" threads in JC. LOL!!1!one!!1

i'll put $20 on a bell curve distribution of iqs.

--
maestro8

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I think Kyle Holmes was on a show on the discovery channel where they
actaully quantified his balance skills. If you could figure out a way
to do that, perhaps you could get 10 or 20 people to try learning, and
test exactly how much an innate sense of balance has to do with
learning to ride. A graph showing balance skill vs. learning time would
be cool. Then write up some stuff about how balance is important to
various animal species or was to the survival of early humans.

Im not sure whether you would have enough time to do this, though. It's
more of a biology thing, so if you are limited to physics it might not
work.

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parapsycho said:

I think Kyle Holmes was on a show on the discovery channel where they
actaully quantified his balance skills. If you could figure out a way
to do that, perhaps you could get 10 or 20 people to try learning, and
test exactly how much an innate sense of balance has to do with
learning to ride. A graph showing balance skill vs. learning time would
be cool. Then write up some stuff about how balance is important to
various animal species or was to the survival of early humans.

Im not sure whether you would have enough time to do this, though. It's
more of a biology thing, so if you are limited to physics it might not
work.

Grr. I meant Kris Holm.

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parapsycho
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Sound good, the most basic test they used was how long you can stand on
one foot with your eyes closed for, i believe an avergae male of Kris's
age can do around 45 seconds, Kris got close to two minutes i think.

--
kington99

Dave

- what a thoroughly post-modern subversion of the cycling genre -
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Erant said:

Sorry, I didn't mean to offend you.

.
.
.

I also think it amazing to find so many physicists (Or at least people
who know quite a bit about it) on a non-physics forum. Maybe that'd be
a good study, amount of people with high IQs on a unicycle 😉

No offense at all. I'm not a physicist, I'm a biogeochemist who studies
soil. But I do enjoy physics.

I like to think unicyclers are a cut above the rest, too!

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JeffArchibald said:

This sounds kind of dumb, but I'm doing a science project on unicycling
and any helpful information would be good.😕

Jeff

Maybe you should do a project about cetri*al force. The discussion and
arguments are here. I can just see the footnote where you identify your
source of information. (1)

(1) www.unicyclist.com/forums

--
Wheel Rider

A man can fail many times but he isn't a failure until he begins to
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Wheel Rider said:

Maybe you should do a project about cetri*al force. The discussion and
arguments are here. I can just see the footnote where you identify your
source of information. (1)

(1) www.unicyclist.com/forums

There are no such things as cetripetal or cetrifugal force. Centripetal
forces on the other hand, do exist.

podzol said:

No offense at all. I'm not a physicist, I'm a biogeochemist who studies
soil. But I do enjoy physics.

I'm no physicist either, but I study electronics. Probably closer to a
physicist then a biogeochemist though, and with an unfair advantage of
having a 3.6kg book next to me, called, very appropriatly "Physics".

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The issue about the (co)existence of centripetal and centrifugal force
is somewhat philosophical. My take at it is this.

Suppose that you swing a marble on a string "in a circle"(*). Suppose
that there is an observer next to you, and that his reference frame is
connected to the solid earth. He will see the marble go round in a
circle, and hence will rightly conclude that a centripetal force is
acting on the marble, accellerating it constantly so that it doesn't
move in a straight line.

So far nothing new.

Now take another observer, a tiny one that is sitting on the marble.
His reference frame is connected to the marble and (part of) the
string. In his reference frame he is sitting still. But this is not
for absence of force! The marble surface exerts a force on him to keep
him from flying off the marble. The force that is acting outwards
(that "tries" to let him fly off) is a centrifugal force. Because the
two forces cancel out exactly, he does not accellerate at all, in his
reference frame that is.

Similarly with forces acting on someone in an elevator. Within the
reference frame of the elevator cage, these forces are real.

F = ma is still fully valid in all cases, but a is measured in metres
per second squared and without reference (!) to a reference frame this
distance in metres cannot be defined.

(*) for an observer on the sun, the marble is not describing a circle
at all, but rather a "slightly wiggly spiraling circle" or so, because
of the motion of the Earth.

Thank you for all of the informaton but I'm only in grade nine and we
don't do physics yet so I don't really understand all of this but I'm
going to get someone older to explain but keep on putting stuff it all
helps.🙂
Jeff

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G-Uni
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