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Re: [Phys-L] playing for keeps



I never thought if this before. And it's one of those out-of-the-blue-yet-how-could-I-have-missed-it connections! It reminds me of how my students react when I tell them that there is a button on their calculator that will give them the slope of a line if they know the angle it makes with the positive-x-axis...

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From: Phys-l [phys-l-bounces@phys-l.org] on behalf of richard lindgren [ral5q@virginia.edu]
Sent: Saturday, June 29, 2013 3:18 PM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] playing for keeps

Good call,
Took me years after grad school when teaching to realize this.
I wonder how many others still don't get it.
Richard Lindgren






On Jun 29, 2013, at 9:54 AM, Richard Taylor <rtaylor.physics@tx.rr.com> wrote:

I imagine he figures everybody knows Avagadro's number. The mass of a proton is the reciprocal.

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Richard Taylor

Sent from my iPad

On Jun 29, 2013, at 8:00 AM, brian whatcott <betwys1@sbcglobal.net> wrote:

On 6/29/2013 7:21 AM, Ken Caviness wrote:
Question for JSD! What method do you use to almost immediately figure out the mass of the proton within 1% accuracy, so you haven't had to take the time and trouble to memorize it? Tantalizing hint (can be done in less time than it takes to ask the question), but I'm drawing a blank -- unless you remember other things more easily, and find m_p from them? (For example, the m_p/m_e ratio, or the nuclear magneton, or ....)
/snip/


I am undoubtedly missing the thrust of Ken's question, but recalling Mp/Me is rather large, I can use the hydrogen mass as a good proxy for Mp.

Brian Whatcott Altus OK
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