Re: [Phys-L] ? FCI --> momentum flow

[John Denker <jsd@av8n.com>]

On 10/21/2013 04:05 PM, Alex F Burr wrote:
> We now have
> Upward flow of upward momentum         [a]
> Upward flow of downward momentum       [b]
> Downward flow of upward momentum       [c]
> Downward flow of downward momentum     [d]
> I am getting confused 
> Of course this my be my fault


Item [b] is the same as [c].
Item [a] is the same as [d].

Yeah, it's confusing, which is why you don't start with
this.  Start with conservative flow of scalars, such as
water (number of water molecules), electric charge,
energy, et cetera.  Once those ideas are reasonbly well
consolidated, move on to the conservative flow of a
vector quantity such as momentum.

You can also start by restricting attention to one-dimensional
dynamics, which greatly reduces the number of possibilities.
Then move on two dimensions, then three, then four.

A big part of teaching involves biting one's tongue, not
saying everything that could be said.