Two questions here. (1) What do you mean by "by 21%"? 21% of what? Of the 10 m/s ground wind speed? Of the 1 m/s headwind? Of the 11 m/s car speed? (2) Why?
You could accelerate the 1 m/s wind as seen by the car to 6 m/s if you wanted, or you could accelerate to 11 m/s, or to any value you like. The question is what the effect would be. In these two examples you'd be accelerating the apparent wind by 5 or 10 m/s, and therefore you'd be slowing the ground wind by 5 or 10 to 5 or 0 m/s. In the first case you would harvest 75%, and in the second 100% of the ground wind's kinetic energy, though there may be (I don't know, I'm speculating) thermodynamic reasons why going for anywhere near 100% extraction is not going to be as helpful as we may hope. Remember, all you need is your prop to generate enough thrust to get your generator to provide enough power. The wheels are being driven at 11 m/s, remember.
Eh? Are you trying to accelerate the air in the wrong direction?
No. The ground air is moving in the same direction as the car. The relative wind seen by the car is moving in the opposite direction. The propeller is accelerating the air in a backwards direction (just like an airplane would do), so the air is going into the prop from the front of the car at 1 m/s towards the prop, and is coming out the back of the prop at more than 1 m/s away from the prop. If you accelerate it by 2 m/s to 3 m/s, this means that the speed of air which has been through the prop, viewed from the ground, will now be travelling at 8 m/s because it has been slowed down by 2 m/s.
Remember: The wind is being slowed (in the sense of losing kinetic energy) from the point of view of a ground observer. For an observer on the car, the wind is being speeded up (in the sense of gaining kinetic energy).
Don't be so sure. Try listing all the items whose energy status is changing, and remember that for any objects which have kinetic energy, the energy quantities depend on where you are observing from.
Not true. This energy comes from the thrust of the propeller pushing the car forwards. Same as it did when the motor was couple to the other axle.
Well, actually a sailing boat *can* sail downwind (but not directly downwind) faster than the wind, but that's beside the point here. The point is that it is the presence of two media in relative motion which make it all possible. That applies to the car too. Without relative motion it would be literally powerless.
By the way, suppose you are in a boat in the middle of a wide river. There is no wind. Can you sail ashore?
Could it be that a car can decelerate at 0.9 or 1.3 times that "g" which is normally given as 9.81 m/s^2? Say, that's a constant, isn't it? Doesn't constant deceleration mean that the speed reduces linearly with time? That for twice the speed we therefore have twice the stopping time? That stopping *distance* therefore varies with the square of speed?
And there we have the proof that you don't understand cars OR physics. Any car on the road can brake at any rate from zero to wheel lockup from 20 mph to zero. The most effective braking is just shy of wheel lockup. Thus you could easily achieve that constant braking force from 20 to 0. Braking from 20 to 0 will take twice as long as braking from 10 to 0.
Wrong.
I think it's fair to say that when I designed and built the Blackbird I effectively answered the energy questions. If you don't think I can answer some specific energy question then by all means ask it. I think we all know why you won't do that.
You do realize that everyone here consistently claims that you're consistently wrong - right?
Wrong again monkey-boy. Everyone here but you understands that what we build demonstrates some fairly basic and well understood principles of physics in a pretty counter-intuitive way. You're the only one that seems to think our vehicle would have to break the laws of physics.
One thing that's become crystal clear is that Dennis is to be used strictly for entertainment purposes. To be fair - I was warned.
So, from their test results it's easy to see that:
60-30mph = 80ft = 1.212 seconds = 1.134g)
30-0 mph = 27ft = 1.227 seconds = 1.120g)
Even Dennis the Dumbass can see that it their tests, it took LESS time to brake the Mustang from 60-30mph than from 30-0mph and LESS than twice as much time to brake from 60-0mph from 30-0mph and the gforces are higher during the initial braking period (just like I told him).
If Dennis the Dumbass' assertion were correct against the baseline
30-0, it would have taken 4.9 seconds to brake from 60-0mph would have consumed nearly 270ft
Don't forget that the *only* place it makes any sense from is the cart. It is using the energy, it is generating the energy from the conditions around it. Now do the physics properly and admit you are wrong.
Yet another diversionary tactic with some total unrelated effect of the current generating wind.
Anyway I am bored with your constant repeating of what is obviously wrong and the diversionary tactics employed by you, and thin rick. Consider yourself plonked along with the rest of the idiots.
The Natural Philosopher gurgled happily, sounding much like they were saying:
If you've got brakes that are fading from a single 100mph stop, you desperately need to get them fixed properly - because they most certainly should not be doing so, no matter what you're driving.
Unless, of course, you've bought the cheapest shittest pattern disks and/ or pads, in which case it's probably to be expected but don't blame the car's manufacturer.
In the limmit the braking on the average car at moderate speeds on reasonably cool brakes is limited by the weight of the car per unit tyre contact area. The 'laws of friction' do not totally apply to tyres. Or you could get the same retardation out of a skinny bike tyre as a flat low profile sports car tyre.
Assuming he brakes are up to it, the tyre is the limiting factor under braking. > 1g is definitely possible. I would guess that 2g is about the limit on a racing style tyre without downforce.
I am sorry, but that is he reality of a brand new car of the sort of shopping trolley variety with a decent load on board.
You have a touching faith in manufacturers.
Nope. A pair of unvented single pot sliding caliper disks and a set of drums on the back, which is what most average small cars have, is only capable or about one emergency high speed stop, especially when 4 or 5 up.. and then the brakes are shot. The steel disk and drums are not capable of dissipating the energy, they must store it as heat increase, and until they cool, there is bugger all left.
That's why you have vented cross drilled disks on sports cars, and so on.
If there was no advantage to them, on the same weight of car (or less) why do they get fitted? Just for show, I suppose you think.
Wow - that's truly atrocious! Were you sleeping at the time? I guarantee I could do that in 1/4th that distance without waking my passenger in my old Mazda. Based on this data point it's pretty hard to take this following claim of yours seriously:
Which just happens to be agree with what I said and he called me stupid for saying it. Nothing that proves he is wrong will be listened too. He will lie about it and claim it is wrong or just plain ignore it and start a new diversionary tactic.
Of course anyone that knows physics will see the energy equations sitting there telling you what happened.
Anyway here is a good one to test ones brain regarding energies (nothing to do with brakes)..
If a car travelling at 100 mph hits an immovable object (say a bridge buttress) is that worse than two identical cars hitting each other head on at 50 mph each?
How about the same car hitting the immovable object at 50 mph?
You're being monumentally stupid again. I could carry on laughing at you, but I'll take pity and explain where you went wrong. "how long to stop" is being taken as time, not distance. Twice the time for the car to stop from twice the speed.
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