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<blockquote data-quote="Ovinomancer" data-source="post: 7493951" data-attributes="member: 16814">Sigh, no, you're saying that a force that exists in either frame changes it's nature because you can't get past the air.&nbsp; In the city frame, the car experiences the same 'headwind' as it does in the car frame, it's just caused by the car's movement against the still air.&nbsp; The same 'wind' is existing either way.&nbsp; It's only because you suddenly see the whole mass of air moving that you want to say it's a new thing called wind.&nbsp; It's not, it's the same thing, just from a different viewpoint.&nbsp; Since it's the same thing, it doesn't change it's nature.&nbsp; Here's a test -- measure the 'wind speed' from the car in both frames without a cross wind.&nbsp; Does it change?&nbsp; No, it doesn't.&nbsp; So, then, why are you insisting that it change when you add a crosswind?&nbsp; The 'headwind' strength is exactly the same in any frame with or without a crosswind.&nbsp; The crosswind doesn't change direction -- you're confusing the shift in appearance of the 'headwind' for an entirely new thing when it's present in the city frame exactly the same way.&nbsp; Force diagrams:City frame:..............'headwind'.....................|.....................vcrosswind -&gt;&nbsp; car &lt;- tire friction.....................^.....................|...............car motorNow, Car frame:..............'headwind'.....................|.....................vcrosswind -&gt;&nbsp; car &lt;- tire friction.....................^.....................|...............car motorAt any instantaneous point, the forces are thus.&nbsp; You can add these forces together, because they are vectors, but that doesn't change their direction, just the direction of your new summation.&nbsp; For instance, you can add the 'headwind' to the tire friction and claim there's now a new force from the top left called headtirewindfriction, but it doesn't change the forces actually working on the car.&nbsp; Same with the crosswind and the motor.&nbsp; Just because you think of the 'headwind' and the crosswind as winds does not make them the same thing.&nbsp; The 'headwind' is static air resisting being pushed out of the way in the city frame, and exactly the same thing in the car frame, only you're calling it a 'wind'.&nbsp; It's not, it's the same thing.&nbsp; The only &quot;wind&quot; in the scenario is the crosswind, and it's present exactly the same way in both frames.&nbsp; You're change frame and confusing yourself as to what's what.&nbsp; Again, I suspected this would happen when this scenario was first proposed, but had the crazy idea I could point it out and get past it.&nbsp; Days later, you're still insisting that 'wind' also means the air resistance from the car's motion, which is the same force in any frame.Gah.&nbsp; You guys are killing me, here.&nbsp; II really thought this would be obvious by now, but it's the same thing.&nbsp; Any chance you'll look at the mooncar example so we might get past this wind thing you're stuck on?</blockquote>

[QUOTE="Ovinomancer, post: 7493951, member: 16814"] Sigh, no, you're saying that a force that exists in either frame changes it's nature because you can't get past the air. In the city frame, the car experiences the same 'headwind' as it does in the car frame, it's just caused by the car's movement against the still air. The same 'wind' is existing either way. It's only because you suddenly see the whole mass of air moving that you want to say it's a new thing called wind. It's not, it's the same thing, just from a different viewpoint. Since it's the same thing, it doesn't change it's nature. Here's a test -- measure the 'wind speed' from the car in both frames without a cross wind. Does it change? No, it doesn't. So, then, why are you insisting that it change when you add a crosswind? The 'headwind' strength is exactly the same in any frame with or without a crosswind. The crosswind doesn't change direction -- you're confusing the shift in appearance of the 'headwind' for an entirely new thing when it's present in the city frame exactly the same way. Force diagrams: City frame: ..............'headwind' .....................| .....................v crosswind -> car <- tire friction .....................^ .....................| ...............car motor Now, Car frame: ..............'headwind' .....................| .....................v crosswind -> car <- tire friction .....................^ .....................| ...............car motor At any instantaneous point, the forces are thus. You can add these forces together, because they are vectors, but that doesn't change their direction, just the direction of your new summation. For instance, you can add the 'headwind' to the tire friction and claim there's now a new force from the top left called headtirewindfriction, but it doesn't change the forces actually working on the car. Same with the crosswind and the motor. Just because you think of the 'headwind' and the crosswind as winds [I]does not make them the same thing[/I]. The 'headwind' is static air resisting being pushed out of the way in the city frame, and exactly the same thing in the car frame, only you're calling it a 'wind'. It's not, it's the same thing. The only "wind" in the scenario is the crosswind, and it's present exactly the same way in both frames. You're change frame and confusing yourself as to what's what. Again, I suspected this would happen when this scenario was first proposed, but had the crazy idea I could point it out and get past it. Days later, you're still insisting that 'wind' also means the air resistance from the car's motion, which is the same force in any frame. Gah. You guys are killing me, here. II really thought this would be obvious by now, but it's the same thing. Any chance you'll look at the mooncar example so we might get past this wind thing you're stuck on? [/QUOTE]

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