Re: Paths against gravity and using gravity vs energy used

"Spaceman" <spaceman@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
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Cwatters wrote:
"Spaceman" <spaceman@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
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>> It takes the same amount of energy whichever route is taken...

So you can take a longer path with the same amount of
energy as the shorter path would have needed?
That won't even work on flat surfaces nevermind
going up hills.
It seems you have a flaw that is pretty wrong.
:)
Sorry.
You are incorrect.


E = m * g * (Height of end - height of start).

Assumptions:

1) The object traversing the parth is 100% efficient.
2) We can ignore secondary effects such as the varaition in local
gravity due to the mountain and the like.

Think again please.
and ignoring gravity is also a big problem.
Or design a car that can do such without the 100% efficiency
part and save oil for all of us.

Duh I'm not that stupid. Obviously in a real world problem one route
might require more energy but you didn't specify the problem in
sufficient detail to allow anyone to calculate which route that would
be.

OK,
My point was to just show that if anything a longer path
will require more energy and when you remove friction,
they are pretty much equal when just fighting gravity alone.

As usual the devil is in the details. You need to specify
all the parameters to make an informed judgement. For
example, the velocity profile along each path; drag effets
can vary in complex ways with velocity. Moving at a snail's
pace along a longer path can take much less energy than
going at a high velocity along a shorter path if drag due
to air friction is a factor. Air drag tends to go up as
the square of the velocity.
.

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