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Q about teaching gravity.


aaabha
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Q about teaching gravity

 

 

 

Hello

 

I came across a secondary school physics teacher recently who said that he explicitely teaches his pupils that gravity is not a force. His reason for this is that gravity is the field and weight is the name given to the force of gravity. This is giving me quite a headache for the following reasons:

 

Pros of teacher's argument:

1) He's right, as in nothing he said was factually incorrect.

2) Looking at the big picture, its kind of good that the teacher had a deeper knowledge of the subject than most science teachers.

 

Cons of teacher's argument:

1) He's just trying to be a smart-rse. I have a physics degree and no-one from my school teachers right up to university lecturers (who listed gravity as a fundamental force) has seen the need to pick apart the language of gravity in such a way. Thus I feel gravity being called a force is accepted by everyone else Ive ever met so why would the teacher be so picky?

 

So the questions Id like answered is does the teacher have a point and more importantly, should he be teaching kids this point? Is it an important distinction like weight/mass or substance/material, or is it just about the English language?

....

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Hahaha you said he was secondry school teacher.. I believe there it should be kept more simple, for the reasons that when I got to my A-levels I was told all that was taught to me in GCSE (secondary school) was a lie. So I think he should stop being so formal with his students and keep it as a force.. Most teachers dont try to smarten up the look of it. So why should he. I think its just another name for it like man, male, men and Female, woman, etc.. I dont think what he has said is wrong.. Just it is not really needed in his classes. But maybe he is just highly spoken.

 

Hope this is helpful.

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By the same reasoning, the Coulomb force isn't a force either. A point charge creates an electric field and the so-called Coulomb force isn't really a force, it's just a name we give to the product of the electric field and the charge on a test particle.

 

So, Bzzzt. Wrong.

 

 

Gravity is a weird beast. Gravitation is a fundamental force in Newtonian mechanics but it is a fictitious force in general relativity. If your teacher acquaintance had talked in this way I would have agreed with him. This topic can be discussed without going into the mathematical details. (The mathematics of GR is are way over the head of most undergraduate physics majors, let alone high school students.) The focus of this non-technical discussion would be the equivalence principle and the concept of weight.

 

Weight, like gravity, is also a weird beast. Weight defined as gravitational acceleration times mass cannot be measured. What your bathroom scale measures is apparent weight rather than actual weight. In Newtonian mechanics, apparent weight is the net sum of all real (non-fictitious) forces acting on an object except for gravity. In general relativity, apparent weight is the net sum of all real (non-fictitious) forces acting on an object, period. Gravity is a fictitious force in GR.

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I came across a secondary school physics teacher recently who said that he explicitely teaches his pupils that gravity is not a force.

 

One can take the view that gravity is not a force, but as DH has stated this is a technical issue that involves the mathematical structure of general relativity. At the secondary school level attempting to make this distinction will most likely just confuse everyone.

 

According to general relativity gravity is viewed as the curvature of space-time.

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Now that a few of the "Physics Experts" have weighed in, from your brief outline, I get the feeling the teacher in question is trying to accomplished exactly what you yourself have expressed, deep thought.

 

I'm constantly amused, when questioning the accepted is itself questioned and often have wondered where science would be today if questioning those accepted ideas, was acceptable, frankly one such topic, 'Gravity'...

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