Ron Hitler Barrassi wrote:
> 
> 
> Kevin Gowen wrote:
> 
>> Ron Hitler Barrassi wrote:
>>
>>>
>>>
>>> Kevin Gowen wrote:
>>>
>>>> Ron Hitler Barrassi wrote:
>>>>> Seems you have "forgotten" your chair example which means you have 
>>>>> realised you were wrong.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> What's to forget? I'll repeat it again:
>>>> If a person with a mass of 100kg is sitting on a chair at rest, the 
>>>> force of gravity's pull is 980 newtons. In turn, the chair pushes up 
>>>> with 980 newtons.
>>>
>>>
>>>
>>>
>>> No. You still think that gravitational force is a "downward" force. 
>>
>>
>>
>> I, like most people, tend to think of the earth's center of mass as 
>> "down".
> 
> 
> I refer you to Newton's Law of Gravity.

Is that the one where "m" is mass in grams?

>>> Read Newtons Law of Gravitation, (ignoring General Relativity) it is 
>>> a mutal force of attraction. 
>>
>>
>>
>> Even a stopped clock is right twice a day.
>>
>>> Earth is pushing up.
>>
>>
>>
>> I thought it was attraction, not repulsion.
> 
> 
> There is a difference between attraction forces and replusion forces?

You can confirm this empirically. Jump off a tall building. First you 
will feel an attractive force, followed by a repulsive force.

Could you explain some more about this mystical action-at-a-distance 
force through which the earth pushes masses away from it?

>> No, the chair is pushing up. That you insist otherwise illustrates 
>> that you do not understand what force is.
>>
>>>> What on earth did you mean when you said "g=1"? What are the units?
>>>>
>>>
>>> I meant 1g. Yes, I was careless.
>>
>>
>>
>> I see, so you meant to say g=1g? Alrighty then.

So what did you mean when you said g=1?

>> Funny, the last time I said that, you made a wise crack about how we 
>> would lose a lot of springs that way because they would be 
>> accelerating off into infinity. That was also around the time that you 
>> said that a spring could not be used to measure a force, even though 
>> that is precisely how many forcemeters work.
> 
> 
> A spring cannot measure one force. It can only measure two forces. 
> Action and reaction. You went off on a semantics.

Yes, a spring can measure two forces. That is how it can be used to 
measure weight.

>>>>> How does a chair magically know when to push up? 
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> The chair knows nothing. It doesn't need to.
>>>>
>>>>> If you add two
>>>>> equal and opposite forces they cancel each other; 
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Yes, which is why the person is at rest.
>>>
>>>
>>>
>>>
>>> (maybe I have to introduce time dilation)
>>
>>
>>
>> Maybe you have to learn about what a force is.
> 
> 
> one, two.

There's an improvement. I wonder when you'll learn the next number.

>>>>> so why does the chair push down? (down being the null length vector 
>>>>> pointing to the center of the earth)
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Push down on what, the earth? Probably because it has mass.
>>>
>>>
>>>
>>>
>>> As we have discussed previously it is now pushing down with a force 
>>> of it's own weight and yours. It doesn't seem to be pushing up at all.
>>
>>
>>
>> Sure it is pushing up. It is pushing up with the same force as my weight.
> 
> 
> which you can't measure.

No, if it exists, it can be measured.

>>>>>  | 980newtons
>>>>> \|/
>>>>>
>>>>> /|\
>>>>>  | 980newtons
>>>>>
>>>>>
>>>>> so we have fab - fba = 0. But yet the chair still pushes down with 
>>>>> a force 980newtons. Seems your highschool idea of physic is missing 
>>>>> something significant.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Maybe you should enlighten me, then.
>>>
>>>
>>>
>>>
>>> Replace the chair with a spring and it's obvious. You and the earth 
>>> are compressing that spring. That pop sound is the sound of the 
>>> cartoon light coming on.
>>
>>
>>
>> Sorry, no light. I have no idea what you are attempting to explain. 
>> The chair is only pushing down with 980 newtons if it is massless.
> 
> 
> That was an explicit assumption you happilyy accepted earlier.

What is "that"?

>> I am glad to see that you realize that a 100kg mass on the surface of 
>> the earth is pulled down with a force of 980 newtons. Much better than 
>> your assertion that a 200kg mass was pulled down with 400 newtons of 
>> force.
> 
> 
> Except for when you lifted it. F=ma.

Maybe you should show us the numbers you are plugging in there to arrive 
at your answer.

> "You pick it up and momentarily there is 400kg [3920N] pushing downo on 
> the chair (you + the bag + the acceleration of lifting the bag)"

No. Again, since I am not traveling at .866c, we don't have 200kg 
magically appearing out of nowhere.

It is nice to see that you realized the acceleration of gravity is more 
than 2 m/s^2. When you said that a mass of 200kg would have a weight of 
400 newtons, that really brought teh laffo.

> Have you forgotten that when you used to weigh your self the scales 
> would indicate very high weights initially? Can't have been that long ago.

How could that be? After all, according to you, a scale does not measure 
force.

>>> A few key points:
>>>
>>> Special Relativity: speed of light, observers agree, speed distorts 
>>> time etc (ignores gravity)
>>>
>>> General Relavitity: (Einstein's theory of Gravity) mass curves 
>>> time/space, gravity bends light, corrects Newton etc.
>>>
>>> I am refering to the time dilation of mass (Gen Rel) which accounts 
>>> for gravity in "normal" situations, not from speed (Spec Rel). "c" 
>>> has nothing to do with it.
>>
>>
>>
>> I see. You did some Googling after the whooshing. Good on you, as you 
>> Commonwealth folk say.
> 
> 
> You think I had to google for that? 

Or you skimmed through A Brief History of Time, or perhaps The Physics 
of Star Trek. I can think nothing else, as your persistence in confusing 
force with work labels you a scientific ignoramus.

> You are projecting again. Admit it 
> Gowen, you had no idea what General Relativity is. I hope you do now.

Yes, I had no idea what it was.

> 5en:
> "Why did you mention Einstein when relativistic physics had nothing to 
> do with your hypothetical? Was I traveling at 87% the speed of light? "

Yes, I said that because you magically added 200kg to the system. What 
other explanation could there be?

>> By the way, I hope you aren't under the impression that relativistic 
>> physics is more advanced than Newtonian physics.
> 
> 
> Advanced? No it is simpler, but it required non-Euclidian geometry.

Actually, it's not simpler, either. Science is not like technology. No 
branch is more or less advanced than another.

> Maybe you should jump Newton and go directly to Einstein. Tensors 
> shouldn't be a problem for you.

Given your ignorance as to what a force is, I question your ability to 
determine the difficulty level of other concepts.

This page is your only hope:
http://www.physicsclassroom.com/Class/circles/U6L4d.html

Start reading at the part that has a cartoon of a man sitting in a chair.

-- 
FAB = -FBA
It's not just a good idea; it's the law.