From: alain245@videotron.ca   
      
   On Aug/17/2020 at 16:03, JF Mezei wrote :   
   > On 2020-08-17 07:03, Jeff Findley wrote:   
   >   
   > I think Mr Fournier's explanation of triangles may have gotten some of   
   > the bit in my brain to align.   
   >   
   > Say you launch from equator to a 45° inclination.   
   > The Earth gives you a 1666kmh push due east.   
   >   
   > Say you head due north till you reach 1666kmh, and then head north east   
   > at 45°   
   >   
   > At the point you turn to 45° you've had equal push to east/north so your   
   > total vector is in line with a 45° acceleration.   
   >   
   > However the addition of 1666kmh due east with 1666 due west yields a   
   > speed of 2356 heading 45°.   
   >   
   > If you had headed east from launch pad, the same fuel burned would have   
   > given you a total speed of 3332kmh instead of 2356kmh.   
   >   
   >   
   > But there is still something which nags me.   
   >   
   > In deep space:   
   >   
   > I accelerate due east for 10 seconds at 100kmh/s. So I reach speed for   
   > 1000kmh in 10 seconds. (beating what a Porshe can do :-)   
   >   
   > I then repeat the same due north. 10 seconds at 100kmh/s.   
   >   
   > I have given energy to reach 2000kmh. Yet, my speed is only 1414kmh. A   
   > loss of roughly 600kmh.   
      
   Yes that is it.   
      
   > Or do the laws of conservation of mass/energy still regard that 1414kmh   
   > speed has being 1000kmh northbound and 1000kmh eastbound and thus energy   
   > conserved?   
   >   
   > Yet, a ship which accelerated directly to 45° will have injected only   
   > 70% of the energy used by the other ship which achieved the same speed   
   > by first accelerating to east and then to north. And that ship will have   
   > the same "triangle" that says it has 1000kmh eastbound and 1000kmh   
   > northbound components.   
      
   I think you are mixing things up here. There is no conservation of   
   energy in that sense. If you are motionless and you accelerate to 1000   
   km/h in one direction then give yourself another push of 1000 km/h in   
   the opposite direction you come to a stop again. You don't have the   
   energy of 2x1000 km/h. And even if you accelerate twice in the same   
   direction, you don't end up with twice the energy of one acceleration   
   (you get four times the energy).   
      
   If you burn your fuel in an inefficient way (inefficient direction) you   
   waste energy.   
      
      
   Alain Fournier   
      
   --- SoupGate-Win32 v1.05   
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