Re: [Phys-l] Student engagement--GAIN

["John Clement" <clement@hal-pc.org>]

Of course your puzzle is not the same because they start at the same time.
But my reply is do you know why the puzzle was presented in the activity?
It has a pedagogical goal.  Incidentally in the book this is the first time
they have been asked to do a kinematic problem, and it introduces motion
maps or what they call a strobe diagram.

I suspect that most students couldn't do the alternate puzzle which was
presented by Brian.

John M. Clement
Houston, TX


> This is a pleasant puzzle, dressed up for obfuscation.
> Say it were presented in this manner:
>
> John sets out to meet Sandra, who is 33 meters away.
> He steps towards her at 1.5 meters/sec. She steps out
>  towards him at the same time, at 2.5 meters/sec.
> There is a lamp post at 18 meters from John's starting
> point. This post is initially 15 meters from Sandra
>  of course.
> Where do they meet, in relation to the lamp post?
> I fancy more kids could answer this algebraically.
>
>  The dressed up puzzle reminds me of the puzzle
> starring an  insect flying to and from between two trains:
> and how far it travels before being  squashed when
>  the  locos collide.   This one too, has a need
>  to be 'unfolded' for ready solution.
>
> Brian W
> p.s. This is not to minimize the conceptual visualization
> value of the graphical approach over the algebraic method
> for the puzzle as given.
>
> John Clement wrote:
> > /snip/
> > Here is a specific problem that students in general either find
> impossible
> > to do, or impossible in a short time to do by algebra. /snip/
> > http://srri.umass.edu/files/mop_samples/Act016.pdf /snip/
> John M. Clement   Houston, TX
>
> > > > Actually there are some problems which  are very difficult using
> equations, and are much easier using either graphs or motion maps.