Hi Ralph,rlortie wrote:"Whether the CF is strong enough to overcome friction and cause outward motion, is a totally other subject."
I'm pretty sure that was the original question, and that's why Jim's reply is as good as insignificant.
c.f question
Moderator: scott
Re: re: c.f question
I'm pretty sure that was the original question, and that's why Jim's reply is as good as insignificant.
-
johannesbender
- Addict
- Posts: 2432
- Joined: Thu Apr 18, 2013 3:29 pm
- Location: not important
the original question was simply in other words
does the weight receive cf from the earth because you would expect it to be there but it is not observed and the answer as I
understood was : yes it does but not enough to move the weight.
so with that said, when i calculate cf of lets say the hand of the clock as jims example , does that also add the small amount of cf of the earth , i ask because thats what i think the formula is suppose to include if we calculate cf on something on earth no matter how small the number but when you calculate something i guess precision would be important
does the weight receive cf from the earth because you would expect it to be there but it is not observed and the answer as I
understood was : yes it does but not enough to move the weight.
so with that said, when i calculate cf of lets say the hand of the clock as jims example , does that also add the small amount of cf of the earth , i ask because thats what i think the formula is suppose to include if we calculate cf on something on earth no matter how small the number but when you calculate something i guess precision would be important
re: c.f question
Don't get me wrong! Cf has its place and does accomplish something. It gets rid of excess water when a washing machine goes into spin cycle, I guess you could call that "work" as it is moving mass measurable in time.
A physical barrier called the tub. is the centripetal force keeping the clothes within the tub. Without outside energy providing the spinning via motor you have nothing. And this is the extent of my thoughts on utilizing Cf as a form of "Motion wheel"
Ralph
A physical barrier called the tub. is the centripetal force keeping the clothes within the tub. Without outside energy providing the spinning via motor you have nothing. And this is the extent of my thoughts on utilizing Cf as a form of "Motion wheel"
Ralph
re: c.f question
If gravity were turned off you would see the effect of CF, and it would not be considered small. If something was not tied down it would fly off into space, you do not need centripetal force for there to be centrifugal force. But without centripetal force centrifugal force will separate pieces from the wheel (earth).
If you tied a rope to a couch and stacked it down, to the east, with a long rope; and then turned off gravity the couch would rise off of the ground and fly up into the air on the end of the rope. The couch's velocity would increase and the spinning of the earth would be reduced (howbeit ever so slightly).
The centripetal force (that is responding to the CF) in the rope would accelerate the couch and decelerate the earths spin.
Anyway: If you were sitting on the couch you would not consider the centrifugal force to be of no consequence, the force would not go unnoticed. It is not that CF is small it is that gravity is large.
If you tied a rope to a couch and stacked it down, to the east, with a long rope; and then turned off gravity the couch would rise off of the ground and fly up into the air on the end of the rope. The couch's velocity would increase and the spinning of the earth would be reduced (howbeit ever so slightly).
The centripetal force (that is responding to the CF) in the rope would accelerate the couch and decelerate the earths spin.
Anyway: If you were sitting on the couch you would not consider the centrifugal force to be of no consequence, the force would not go unnoticed. It is not that CF is small it is that gravity is large.
-
eccentrically1
- Addict
- Posts: 3166
- Joined: Sat Jun 11, 2011 10:25 pm
oh man.
yes, you need centripetal force for a reactive centrifugal 'effect'.
that would be the earth spinning.
if you turned off gravity, stopped the earth's spinning, you would still ride along on the surface of the earth. you wouldn't fly off. you could push yourself off, though, because somebody turned off gravity.
yes, you need centripetal force for a reactive centrifugal 'effect'.
that would be the earth spinning.
if you turned off gravity, stopped the earth's spinning, you would still ride along on the surface of the earth. you wouldn't fly off. you could push yourself off, though, because somebody turned off gravity.
re: c.f question
I did not mention stopping the earth's spinning. And you would fly off; you are traveling about (all numbers rounded) 1000 miles per hour (at the equator) tangent to the circle of the earth, after an hour that would take you 120 miles into space.
CF comes first; centripetal is a reaction force to CF. At least it seems that we need to look at it that way. But I will admit that until the rope tries to pull the couch back there is no force involved whatsoever. The couch would move into space without the application of outside force. When the rope pulls upon the couch the rope finds that the couch has CF. Until the rope pulled the couch; the CF was not pulling on anything. But I think we will have to assume that the capability was there: and so to speak the force was there. It is the couch that originates the pulling.
CF comes first; centripetal is a reaction force to CF. At least it seems that we need to look at it that way. But I will admit that until the rope tries to pull the couch back there is no force involved whatsoever. The couch would move into space without the application of outside force. When the rope pulls upon the couch the rope finds that the couch has CF. Until the rope pulled the couch; the CF was not pulling on anything. But I think we will have to assume that the capability was there: and so to speak the force was there. It is the couch that originates the pulling.
-
eccentrically1
- Addict
- Posts: 3166
- Joined: Sat Jun 11, 2011 10:25 pm
re: c.f question
ecc...1
If you turned off gravity you would have a new asteroid belt.
can you not see any problems with the cf formula being applied to the spinning earth?.
It is usually associated with say a ball on the end of a string and the mass in the formula being the ball, but the mass causing the spin : a motor is ignored.
Am I right or not? :))
If you turned off gravity you would have a new asteroid belt.
can you not see any problems with the cf formula being applied to the spinning earth?.
It is usually associated with say a ball on the end of a string and the mass in the formula being the ball, but the mass causing the spin : a motor is ignored.
Am I right or not? :))
-
eccentrically1
- Addict
- Posts: 3166
- Joined: Sat Jun 11, 2011 10:25 pm
not.
centripetal acceleration applies to the spinning earth even though the earth doesn't have a motor inside it.
pequaide brought up gravity being turned off, read more of the posts.
the formula for ca is F=mass x velocity x velocity / radius.
that is the relationship between the mass , velocity and radius. It is the same relationship for every system including bessler's wheel.
http://en.wikipedia.org/wiki/Centripetal_force#Formula
centripetal acceleration applies to the spinning earth even though the earth doesn't have a motor inside it.
pequaide brought up gravity being turned off, read more of the posts.
the formula for ca is F=mass x velocity x velocity / radius.
that is the relationship between the mass , velocity and radius. It is the same relationship for every system including bessler's wheel.
http://en.wikipedia.org/wiki/Centripetal_force#Formula
re: c.f question
You are traveling 1000 miles per hour tangent, and you are going to fly off of the earth even if (at that point) you stop the spinning. It is the moving couch that causes the force.
re: c.f question
ecc...1
Ok thank you I just wanted to see how you would answer.
Ok thank you I just wanted to see how you would answer.
-
johannesbender
- Addict
- Posts: 2432
- Joined: Thu Apr 18, 2013 3:29 pm
- Location: not important
if i could translate this somewhat diffrently (excuse me for being a fool) in the earth gravity would act as cpf ? or gravity wins the cf ?
on earth gravity acts towards the centre keeping everything heading in only towards one direction not taking into account orbital movement ...
on a wheel on earth gravity acts towards the centre of earth and would assist any weight movement towards the bottom of the wheel and cf if enough rotation speed is present would push outward away from the centre so if
gravity assisted a weight moving down and cf pushes a weight away from the wheel centre then on the bottom half of the wheel , you would find that cf and gravity combined together in moving the weight away from the centre but
on the top gravity will do the opposite and fight against cf , so therefore only the oppisite will ever be achieved (oppisite of what you expect a lever/weight system would do in motion/rotation) and therewithin lays one of the biggest problems of pm because you are working against the oppisite situation on top ...
edit..if you try pushing a weight in towards the centre in the bottom you fight cf and gravity ..
if you try pushing a weight away from the centre on top you fight gravity ..
if the wheel spins to right , on the right cf assists pushing a weight out but on the left you fight against cf ..
on the right gravity assists but on the left you fight gravity ...
on earth gravity acts towards the centre keeping everything heading in only towards one direction not taking into account orbital movement ...
on a wheel on earth gravity acts towards the centre of earth and would assist any weight movement towards the bottom of the wheel and cf if enough rotation speed is present would push outward away from the centre so if
gravity assisted a weight moving down and cf pushes a weight away from the wheel centre then on the bottom half of the wheel , you would find that cf and gravity combined together in moving the weight away from the centre but
on the top gravity will do the opposite and fight against cf , so therefore only the oppisite will ever be achieved (oppisite of what you expect a lever/weight system would do in motion/rotation) and therewithin lays one of the biggest problems of pm because you are working against the oppisite situation on top ...
edit..if you try pushing a weight in towards the centre in the bottom you fight cf and gravity ..
if you try pushing a weight away from the centre on top you fight gravity ..
if the wheel spins to right , on the right cf assists pushing a weight out but on the left you fight against cf ..
on the right gravity assists but on the left you fight gravity ...
re: c.f question
johannesbender
You are totally correct! and all you have to keep in mind when building. Good luck on your builds.
You are totally correct! and all you have to keep in mind when building. Good luck on your builds.
-
eccentrically1
- Addict
- Posts: 3166
- Joined: Sat Jun 11, 2011 10:25 pm
Re: re: c.f question
backwardspequaide wrote:You are traveling 1000 miles per hour tangent, and you are going to fly off of the earth even if (at that point) you stop the spinning. It is the moving couch that causes the force.
it's the earth that causes the force. your couch's 'force' is dependent on the earth's spinning; not the other way round. the reference frame of your couch is attached to the earth system; any macro scale motion it has refers back to the earth. the earth (and its atmosphere) is the working mass in most everything we do.
http://en.wikipedia.org/wiki/Working_mass
In more "down to earth" examples the working mass is typically provided by the Earth, which contains so much momentum in comparison to most vehicles that the amount it gains or loses can be ignored.
yes?In many cases the working mass is separate from the energy used to accelerate it. In a car the engine provides power to the wheels, which then accelerates the Earth backward to make the car move forward.
re: c.f question
Johannesbender don't forget time; gravity (as any force) is a function of time. When you have a (outside the wheel) throw from 12 o'clock the missile direction is tangent to the wheel (horizontal). Gravity will assist until the missile is under the wheel at 6 o'clock. By then the motion of the missile is very fast and it will rise over a shorter period of time to cover the distance it has fallen.
The motor does not provide the CF or the CP to a spinning system, because it does not need to. Both CF and CP are free forces. The motor provides the energy needed to move the mass in a straight line.
The motor could be a chain drive that initially moves the mass linearly and then the motor disconnects and the mass is moved into a circle, the CF and CP are free and the mass maintains a linear equivalent of motion. If the mass is released from the circle it will have its original linear velocity.
CF/CP can transfer motion from the wheel to the missile but these forces cannot increase or decrease the total motion (mv) of the wheel. CF/CP can be very large and can transfer motion quickly. But no matter how large they never increase the total motion (mv) of the wheel.
But the transfer of momentum from a large mass to a smaller mass can increase the energy of the system. A 10 kg wheel moving 1 m/sec is 5 joules: a 1 kg missile moving 10 m/sec is 50 joules, but they have the same momentum.
The motor does not provide the CF or the CP to a spinning system, because it does not need to. Both CF and CP are free forces. The motor provides the energy needed to move the mass in a straight line.
The motor could be a chain drive that initially moves the mass linearly and then the motor disconnects and the mass is moved into a circle, the CF and CP are free and the mass maintains a linear equivalent of motion. If the mass is released from the circle it will have its original linear velocity.
CF/CP can transfer motion from the wheel to the missile but these forces cannot increase or decrease the total motion (mv) of the wheel. CF/CP can be very large and can transfer motion quickly. But no matter how large they never increase the total motion (mv) of the wheel.
But the transfer of momentum from a large mass to a smaller mass can increase the energy of the system. A 10 kg wheel moving 1 m/sec is 5 joules: a 1 kg missile moving 10 m/sec is 50 joules, but they have the same momentum.