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You need to learn to read. I never suggested the need for an additional power source for the car between the conveyors.
Quote from: Halc on 19/06/2021 12:54:56You need to learn to read. I never suggested the need for an additional power source for the car between the conveyors.You haven't retracted your claim that the land yacht needs a battery to go faster than the wind.
When the size of the pulleys are equal, we get back to my previous picture. Tip speed of bottom wheels are 1 m/s. The car would be stationary wrt observer, or 1 m/s relative to bottom conveyor. With 2:1 ratio, the car would move 2 m/s relative to bottom conveyor, or 0 m/s relative to top conveyor.
With 3:1 ratio, the car would move 3 m/s relative to bottom conveyor, or 1 m/s relative to top conveyor.
When the ratio is negative, like in 8 figure V-belt, the car would move backward.
You need to learn to read. See post 31.
I read the line in the article: "the rotor (acting like a wind turbine)" to mean that the air drove the propeller, the energy of which was sent to the wheels, which violates energy conservation per my post above. But reading closer, the opposite is what is going on. The rotor acts as a propeller, not a turbine. The wheels apply a braking action and the propeller applies thrust. Thus energy is taken from the air movement and no violation of energy conservation takes place.
If it's moving at 0 m/sec relative to the top conveyor, the wheel would not be turning at all, which contradicts a 2:1 ratio between the turn rates of the two wheels. Your algebra is off.
vc : speed of the carvbc : tip speed of bottom wheels relative to the carvtc : tip speed of bright wheel relative to the carvt : tip speed of bright wheel touching top conveyordvt : speed difference between highest point of bright wheel and top conveyor
Your assertion contradicts the algebra. If you want the assembly to move left, the lower pulley needs to be the larger one, regardless of regular or figure-8 looping of the belt.
Here is an interesting thing. With ratio=-1, dvt is constant. No matter how fast the car is running, it will always feel a push to the right by top conveyor. It seems like the only force countering it is friction. Traction between bottom wheels and conveyor can be a limiting factor. So does the slipperiness of the bright wheel.
The twisted belt can be replaced by gears to achieve the same effects.
This is equivalent to the twisted belt with identical size pulleys top and bottom.In such an arrangement, there is no speed at which the one wheel will not forever slip at dvt=2.The size of the yellow idler gears has no effect on the relative rate of turn of the wheels. The only size that matters is the red gears, and you drew those the same.You also drew the arrow for the large yellow gear larger than the smaller one. The smaller one will turn faster, but indeed, the actual wheels with the red gears will turn the fastest as you have drawn them.
The left image shows straight pulleys with positive ratio, while right image shows inverting pulleys with negative ratio.
Professor @alexkusenko has graciously conceded the wager.Changing your mind in light of new evidence is the hallmark of a great scientist.I want to thank Alex for the many good points he raised, which have sharpened my thinking about this problem. https://t.co/UEzYHsYjd9
Here is a diagram showing the setup from the video. No slippery wheel is used. Instead, to simulate wind, the top conveyor can be made slippery. All wheels are non-slippery type. The ratio is inverting.
Not quite. Note the two different radii of the spools used in the video. The are key to have it move faster than the ruler. I'm attaching the diagrams for various examples, including the formula to compute their speed.
Quote from: MarkV on 24/06/2021 15:57:47Not quite. Note the two different radii of the spools used in the video. The are key to have it move faster than the ruler. I'm attaching the diagrams for various examples, including the formula to compute their speed.What would happen if R=r?
In the frame of Earth, the rotor accelerates the air since it is pushing from behind.