Ok, You can be convincing. I agree, I was wrong with the post. What
else am I expected to say?


>>> I don't understand how you get from force to momentum. In this case,
>>> neither the earth nor the plane have a vertical momentum. (Imagine
>>> the earth as large enough so that the non-flat shape of its surface
>>> doesn't matter.) So neither goes into the momentum preservation
>>> calculation.
>>
>> That's wrong statement "neither goes into the momentum preservation
>> calculation" as the assumption "neither the earth nor the plane have a
>> vertical momentum" is wrong. They have variable momentums strictly
>> within momentum preservation low.
>
> (I assume you meant "momentum preservation law".)
>
> You seem to have forgotten to consider that our assumption is that the
> plane flies with constant speed at constant height ("height" meaning
> "distance from Earth surface").
>
>> Imagine a plane is a molecule, air is molecule and Earth is a molecule
>> too. Plane and Earth will be playing ping-pong, a ball being an air
>> molecule. Clearly Plane and Earth will be experiencing variable
>> momentums. You can glue more molecules into each object, this will
>> affect numbers, but physics would remain the same - variable
>> momentums.
>
> We assumed a plane flying at constant height. How it got there is
> another question for another day, and what it does once fuel goes out
> (or shortly before :) is also another question for another day -- maybe.
> But for now, I was only looking at the time where the plane flies with
> constant speed at constant height.
>
> The second issue to consider is the reference system. In order to talk
> about speed, you need to say "speed relative to ...", where "..." is
> called the "reference system". I chose the Earth as the reference
> system. Being the reference system, its speed and therefore its momentum
> in this system is by definition zero. Since I assume a plane flying at
> constant height, its vertical speed and therefore its vertical momentum
> is also zero -- in this reference system.
>
> Gerhard
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.