Ron Hitler Barrassi wrote:
> 
> 
> Kevin Gowen wrote:
> 
>> Ron Hitler Barrassi wrote:
>>
>>>
>>>
>>> Ron Hitler Barrassi wrote:
>>>
>>>>>> If that is the case, why did you suggest using a spring based 
>>>>>> device to measure the downward force 
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Because I have heard of Hooke's Law.
>>>>>
>>>>
>>>> But not the gravitional constant apparently.
>>>>
>>>>
>>>>>> when the correct way to measure force is it's effect on moving *a* 
>>>>>> body of mass?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> It's "effect"? I don't even know what that is supposed to mean. Who 
>>>>> says that a mass acted upon by a force must be in motion? Push 
>>>>> against a building as hard as you can. The building does not move, 
>>>>> but you are still exerting a force upon it.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> F=ma
>>>>
>>>> (I've highlighted the definite article to draw attention to your 
>>>> misreading)
>>>>
>>>
>>>
>>> I didn't elaborate on this point. You cannot use a spring to measure 
>>> a force. 
>>
>>
>>
>> Really? Don't tell Hooke.
>>
>>> It can only be used to measure weight (NB deliberate use of "weight", 
>>> not "mass" not "force", but "weight". 
>>
>>
>>
>> Weight is a force.
> 
> 
> Weight is a scalar. Force is a vector. 

Weight, being a force and having magnitude and direction, is a vector.

> You don't weigh in the direction 
> of anything.  

In this planet, your weight is a force vector in the direction of the 
earth's center of mass. This is why you place a scale beneath you rather 
than on top of your head.

> As you are in Florida your weight is in a different 
> direction to mine? (I'll let you off this one)

Yes.

>>> A spring, like your tug of war rope, requires a force at both ends to 
>>> expand, or contract.
>>
>>
>>
>> Yes. In the case of a bathroom scale that measures weight with a 
>> spring, the person standing on the scale provides the force at one 
>> end. The floor beneath the scale provides the force at the other end.
>>
> 
> You missed the definite article again.

You called "a" the definite article again.

> If a force act on a spring the spring will accelerate off in the 
> direction of the force. We would lose a lot of springs that way. 

A force need not result in motion. Compress a spring between your thumb 
and a finger. Force is acting on the spring, but strangely, it does not 
go accelerating off into infinity.

You also may wish to drive an automobile into a brick wall at a high 
velocity. You will exert a force on the wall, but it will not move.

> Newton's 3rd I believe.

I only wish you would believe it.

> So it is measuring two forces? More magic forces appearing from nowhere.

This is just too funny.

- Kevin