Sort of. One of the equations of motion is that the total energy is conserved - i.e. it doesn't change with time. But that doesn't tell you what its value is, of course. When you boost, you change the value of the total energy, but in any frame it's conserved.
Right: energy is relative. Technically speaking it's the time component of a 4-vector, which means it isn't invariant under coordinate transformations like boosts.
Right, I think that's starting to get clearer to me. Thanks again.
Windspeed for the cart is said to occur when there is no differential velocity between the cart and the wind. The other definition is that the cart is traveling at the same velocity as the measured velocity of the wind.
Humber, I really think you should consider ducking out now, before you dig any deeper hole for yourself. Either you understand that the two above definitions are exactly the same, and are pretending not to, or you don't. Either way, you're not in a position to argue with people who don't deny it.
As long as the second definition is met, then I am not concerned about the other.
Since they are the same, if one is met, the other is. The only possible suggestion of difference is again from your insistence on measuring velocities from your earthbound bias, and, although they are still exactly the same definitions, the phrase "the same
measured velocity" could be used to imply that only a non-zero value could be measured. The equivalence of frames of reference (boosts or whatever) has been explained time and time again and either you deny it or do not understand it, which would explain the above mistake.
I must have forgotten to click to mutli-quote your original point about the "bias" of the prop, but here again is a demonstration either of a lack of understanding of the basics of how a few gears work, or a troll's pretense of same. The CW or CCW turning of the prop is not in itself significant, only how it pushes the air - forwards or rearwards. If you like, you could take the gear connection at the wheel-propshaft and make that of the opposite sense, by, for instance putting the gearwheel turning with the vehicle's wheel on the other side of the wheel. This would change the push of the prop by changing it's rotation. However, if you used a prop with the opposite twist (pardon me, this won't be the tech term) - so it has a pitch of the opposte sense or sign (you can't turn it round on the shaft, it has to be a different prop or one of variable shift), then these two opposite changes (gear and pitch) will cancel each other out. You would now have a prop that turns the other way, but still pushes air backwards, in the case under discussion. Again, not understanding these basic points is reason to quit while you're not out of pocket.
As mender explained wrt the test, the significant bit is just:
<snip>and pitched so as to move air front to rear relative to the prop?
Further demonstration of your failure to understand comes with your response:
Yes, that is the same as the other videos. When driven by the belt, the propeller rotates CW, when viewed from the rear. Perhaps I can put it another way. If the wheels are driven CW as on the belt, in which direction is the thrust generated, and is that more or less than the thrust when the wheels are driven CCW?
It is fine to describe clock rotations of the prop wrt "looking from the rear", but then you try to describe wheel rotations, without mentioning which side of the machine you are looking at, which is meaningless.
Just had this brief conversation with my son . . .
Son - “So you’re going to spend time and money building this thing that you’re fairly sure won’t work?”
Me - “Yes”
Son - “And even if it does work it doesn’t have any practicle use?”
Me - “Yes”
Son - “ Are you sure you’re my father?”
Me - “Ask your mother.”
I'm surprised. I thought you'd shifted to those who believed it works. I certainly have. Well, I was at 99% sure, and it's going up from there.
Yes, I agree. I said 'wind' , on the understanding that we were looking for an indoor solution, so 'airflow' is perhaps the term I should have used.
The treadmill can only provide wheel drive, so I am wondering, how?
You will continue to wonder how until the penny drops regarding boosts and relative motion, if it ever does, or, if it already really has, when you stop trolling.
Thinking it over, I realize that my earlier statement that my cart would work without the wheels was wrong. Anyway, I've also realized that I can make my cart simpler (by removing the chain and getting rid of a cog) and easier to understand. Here's the updated version...
Actually, a better way of looking at gears is as if they were levers. The axle acts as the fulcrum. The distance from the axle is the length of that end of the lever. Since the cogs have a shorter distance from the axle than the wheels, they act like the short end of the lever.
Here's what looking at the new cart's wheels as levers looks like...
ETA: Notice, the top wheel isn't doing anything except changing the direction.
I've had difficulty with these, Brian, because of the conveyor belt's direction of travel, which appears to oppose the direction of the side of the upper wheel it is in contact with. I imagine this is my failure to understand the diagram. It seems there's something odd going on here. I can imagine dropping the belt so that it turns the bottom of the wheel, or the top of the inner wheel of the set below, but then it changes the sense as related to how a wheel with flopping vanes would be pushed by the air faster than the air (sorry, forgotten who posted that now - which I stupidly criticised wrongly - the one next to a man). In that design, it was the fact that the vanes were propelled by the wind below the axel that meant they moved slower than the wheel rim, and allowed DDFTTW.
I think this problem may be something to do with your diagram showing a part of the effect or something, but I can't quite work it out. I wonder if it's because your diagram relates the workings of one part of the system.
Actually, for those interested in investigations of the cart's workings by practical testing, that flopping-vane design might be useful with two wheels, or a four-wheel cart arrangement. It could even be placed in a steady stream of water in a suitable ditch (sinking well below the surface) because the flow might be more obviously linear and the direction unchanging, unlike the outdoor wind, and because long ditches aren't so hard to find as long pipes of air - it should then be shown to travel faster than the water in the ditch. Just a thought.
Another - everyone's concerned about all the eddies in natural winds. I just wondered if there's anywhere (easy to reach) where winds are known to blow without such disturbances?
