Re: [Phys-l] definitions ... purely operational, or not

[William Robertson <wrobert9@ix.netcom.com>]

I understand what you're saying, but my remedy is different. To  
understand why astronauts say they are weightless, we have to  
understand that they are viewing things from a different frame of  
reference in which there is no gravity. As I said before, I think it's  
better to address the issue head on rather than use a different  
definition of weight. By the way, the folks at NASA and astronauts  
increasingly use the term "microgravity" in an effort to clear this up.

Bill


William C. Robertson, Ph.D.


On Nov 9, 2010, at 1:16 PM, LaMontagne, Bob wrote:

> The direct result of that approach, i.e., that weight is  
> gravitational pull, is that students will assume there is no gravity  
> in space because astronauts are "weightless". In fact, one hears  
> students saying that frequently. I hear it most from my meteorology  
> students rather than my general physics students because that is  
> what they took away from their high school physics course (weight is  
> gravity).
>
> Bob at PC
>
> ________________________________________
> From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu 
> ] On Behalf Of William Robertson [wrobert9@ix.netcom.com]
> Sent: Monday, November 08, 2010 11:00 PM
> To: Forum for Physics Educators
> Subject: Re: [Phys-l] definitions ... purely operational, or not
>
> My specific take on it is that it works just fine. My particular
> interest now is how teachers view the definition and how it affects
> students. Like it or not, most elementary and middle school students
> learn the difference between mass and weight as the fact that mass
> does not change when we go to the moon, but weight does. That only
> works if weight is defined as the force of gravity acting on an
> object. If weight changes all the time depending on the viewer's frame
> of reference, then all we have is confusion for the students. When we
> say that objects "weigh less in water" or other conventions, then it's
> confusing for students. Even young students can understand relatively
> abstract ideas, but not if we all use different definitions.
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