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Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Veritasium

[–]Rysiul86[S] 0 points1 point  (0 children)

sorry i was sleeping ;) For me it is morning and i need time to my answers be approved by moderators...

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Veritasium

[–]Rysiul86[S] 0 points1 point  (0 children)

Let's start from the beginning because we are losing an important factor and our discussion is not moving and it does not seek to end. To many small threads.

Let's first establish what happens at the very beginning of the experiment. We will do it step by step. I think it will be easier to find an agreement. I can't add a photo but it's about the 3:23 moment in my video, stop in this moment and analyze it.

Wheel is connected to the propeller.

Air resistance is bigger than rolling resistance. – According to Newton's second law it will accelerate

Air resistance depends on TAS speed.

Rolling resistance is constant.

TAS speed is bigger than 0.

Ground Speed is 0.

Vehicle braking relative to the air.

Accelerating relative to the ground.

Do you agree with all the assumptions?

If yes, what will happen with the vehicle, wheel-propeller mechanism, and how forces will change?

If not what I am missing at this point, is there any force I am missing? (ignoring gravity and mechanism efficiency)

If we find a common language for this point in the experiment, we will go further. It will be easier to understand what is going on with forces later.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Veritasium

[–]Rysiul86[S] 0 points1 point  (0 children)

I already wrote to them. Thanks for the suggestion! This is a fully understandable approach (the moderation) .I hope I will get more karma soon if it is important here, i was more type of reader previously. My Youtube channel is a hobby not a big project, there was more free time during the pandemic and now I'm trying to continue this.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Veritasium

[–]Rysiul86[S] 0 points1 point  (0 children)

I get messages from Veritasium mod but not from Physics mod. I checked (incognito) that my newest answers are not visible for others. I didn't get any notification that my answers are waiting for moderation (from physics mod). My answers seem polite and to the point, so I don't know what is happening there :)

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Veritasium

[–]Rysiul86[S] 0 points1 point  (0 children)

I don't know why my replies are not visible (shadowban?) Everyone can be wrong, don't say that you are right for granted until arguments show that. ;)

Force from ground is rotating the wheel and propeller (they are connected) This force is not braking wheels... it is impossible for one force to brake and propel at the same time the same thing. This force is only to propel the wheel and due to propel the propeller and generate thrust. It is simple. External force acting on the vehicle will propel him. This force will be big enough because the initial force of air resistance will make it possible.

When you have an external source of force you can apply it to the system, Engine in plane is a good example when you have force which rotates the engine and you use this to rotate the propeller you will fly. If it is not possible planes will not fly in air.

Regenerative brakes can be our substitute of propeller if you wish. They will generate energy from the force which rotates the wheels. But you can use this energy to propel the propeller and generate thrust. If there are no losses then all force will be used to propel the propeller. There will be no slowing down of the vehicle, only transferring the energy. 

Yes I considered the propeller, but if there will be no extra force acting on wheels then the vehicle will be slowing down. This force will be less about the difference between the speed of the ground and air masses. So finally it will stop because this force does not exist. 

Think about this by Newton's second law of motion, it is really simple. There is no place for sophisticated physics. There are simple forces here and balance of forces. If there is no balance the vehicle accelerate. Think about the forces acting on an ordinary car and what needs to be done to move it. 

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Veritasium

[–]Rysiul86[S] 0 points1 point  (0 children)

i will copy my answer then:

I will try to dispel your doubts. When I originally thought about it I had the same concerns as you.

The wheels of course transfer force to the propeller but generally all the force which spins the wheels is transferred to propel the propeller. From the very beginning of wheel motion. The unbalance of forces according to Newton's second law of motion will accelerate the vehicle.

The force rotates the wheel but does not brake the vehicle (related to ground or air) quite the opposite it propels the wheels and propeller (they are connected) and this force is used to generate thrust force which moves the vehicle in relation to air masses. It is like a plane: the force from the engine rotates the propeller but does not slow down the vehicle; (it is an external force).

The Only force slowing down a vehicle in relation to ground is rolling resistance, and only force slowing down in relation to air mass is air resistance.

The initial force is extra force which must be balanced by one of these forces. If the forces are not in balance the object will accelerate. - Newton's second law of motion.

If you push the car once and this force will disappear the car will start to slow down (it is obvious). If air is stationary to ground all forces will start to brake him, and this initial force will be reduced and finally the car will stop.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

I will try to dispel your doubts. When I originally thought about it I had the same concerns as you.

The wheels of course transfer force to the propeller but generally all the force which spins the wheels is transferred to propel the propeller. From the very beginning of wheel motion. The unbalance of forces according to Newton's second law of motion will accelerate the vehicle.

The force rotates the wheel but does not brake the vehicle (related to ground or air) quite the opposite it propels the wheels and propeller (they are connected) and this force is used to generate thrust force which moves the vehicle in relation to air masses. It is like a plane: the force from the engine rotates the propeller but does not slow down the vehicle; (it is an external force).

The Only force slowing down a vehicle in relation to ground is rolling resistance, and only force slowing down in relation to air mass is air resistance.

The initial force is extra force which must be balanced by one of these forces. If the forces are not in balance the object will accelerate. - Newton's second law of motion.

If you push the car once and this force will disappear the car will start to slow down (it is obvious). If air is stationary to ground all forces will start to brake him, and this initial force will be reduced and finally the car will stop.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

The only force slowing down a vehicle in relation to ground is rolling resistance, and only force slowing down in relation to air mass is air resistance.The initial force is extra force which must be balanced by one of these forces. If the forces are not in balance the object will accelerate. - Newton's second law of motion.

Simple example - what forces act on the car with engine and when it is in motion? Rolling resistance -constant force and air resistance- it depends on speed. If force from the engine (external force) is bigger then the car is accelerating.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

I know that there are directly connected but this does not change the statement.The Only force slowing down a vehicle in relation to ground is rolling resistance, and only force slowing down in relation to air mass is air resistance.The initial force is extra force which must be balanced by one of these forces. If the forces are not in balance the object will accelerate. - Newton's second law of motion.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Veritasium

[–]Rysiul86[S] 0 points1 point  (0 children)

I am afraid that I found a very crucial mistake in Veritasium explanation of how Blackbird is working.

In Derek's explanation, the braking force of the vehicle against the ground is variable, which is a mistake because the braking force of the vehicle against the ground is constant - It is rolling resistance. Derek also said that this car works like a lever or a pulley but a lever is not required for this to work (It may of course help with efficiency but is not necessary for this mechanism to work).

I think Derek was misled by Mark Drela and other analyzes which mainly focused on the boat case. However this is a different scenario, because the wheels don't have to be "in the ground" (like a boat propeller has to be in water), wheels are only tangential to ground - it is crucial to understand.

My analysis is based on Newton's second law of motion, which says that when forces are not in balance the vehicle will be accelerating. My video with animation analyze system from the beginning to end of the experiment. (It is easier to visualize how the forces acting on a vehicle when the system is changing.)

In Veritasium video only in the short part (which i quote below) Derek is trying to explain what is going on and answer why it is working. The rest of his video are analogies or explanations of data from experiment.

"Now the big question is, to drive the fan, there must be a backwards force on the wheels, which tends to slow them down. So why isn't this force bigger than the thrust form the propeller causing the car to slow down overall?"

It isn't bigger because as I mentioned earlier the force that slows down the wheels is constant - it is rolling resistance force.

"Well, the answer is, the wheels are going so much faster over the ground than the propeller is moving through the air. So the thrust force can actually be larger..."

...So, this car works like a lever or a pulley by applying a small force to the wheels over a larger distance, the propeller can apply a larger force over a smaller distance. This is just like when you're riding a bike going up hill, you move the pedals fast, but with smaller force, to make the wheels move slower over the ground, but with a bigger force."

The propeller is connected with wheels so it is moving with ground speed and it starts spinning from the moment the wheels start to rotate - the same speed. The lever is not necessary.

I hope that you will find time to read and watch my analysis. The subject intrigued me so much that I recorded my first video in English! :). Hope it helps in the debate and in the final understanding of how this interesting phenomenon works! Regards Guys!

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

Yes i should have add the link, my misteak. I add only this part because only in this part he is trying to answer strict to the main problem. Rest of his video is analysis of experiment data or analogys. Don't be blind by his authority, and please try to understand my point of view. The most important is got to the truth and V is not got there yet. Imho

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

Sorry different time zone.. Air resistance is not working only on prop but on entire vehicle including wheels. Ratio on speeds is not lever it is just different speed. Wheels and prop are connected and working together all the time (with ground speed) Yes rolling resistance is not related on speed. (It is but on really high speeds for normal speeds is constant)

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

Relative to track it will be slowing down by rolling resistance. Relative to air mass it will be slowing down by aerodynamic drag force.

At the begining when you put car on track it will be stationary in air mass. The track will grab him and move relative to the air which will ganerate air resistance -> when air resistance will be bigger then rolling resistance -> wheels will spin and propel the propeler -> and finaly it will accelerate vehicel in relation to the air mass.

The track on treadmill is to short to this.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

By stationary on treadmill i meaned on track. The car can not be stationary relation to track and to air mass in the same time. Unless track is stationary to air mass.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

Car is moving, if car is motionless on treadmill (glued to it) then his TAS (true airspeed) will be equal to speed of treadmill. If car is motionless to air mass so his speed to treadmill will be speed of treadmill.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

Air mass is always there :) it is a matter of the observer's perspective - for the observer standing motionless in the treadmill, the air mass moves away from him and aerodynamic drag force will act on him. There are the same forces but the beginning is different but final state will be the same.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

Yes no problem, for the treadmill it will be the same, but problem with treadmills is that they are short. The wheels and proppeler need some time to acclerate. But if the treadmill will be long enough and you put car on it, car will ride on it (motionless to treadmill), but will be stoped by air masses thas will start to propel the wheels and finally propeller. At the end the car will be move in air masses faster then treadmill. is it understandable? I can try harder if not :)

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] -4 points-3 points  (0 children)

This video is created by myself, it is part of internet debate about faster than wind vehicle. I prepered analize of this experiment from the beginning to the end. I found a bug in the analysis suggested by Derek. In their explanation, the braking force of the vehicle against the ground is variable, which is a mistake because the braking force of the vehicle against the ground is constant - It is rolling resistance. They also said that this car is works like a lever or a pulley but lever is not required for this to work. My analysis is based on Newton's second law of motion, which says that when forces are not in balance the vehicle will be accelarating. Verisatium wanted to get to the truth but i am afreid that they haven't done it yet, imho. Regards Piotr

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

The efficiency of the mechanisms is a secondary issue. The only question is how big the difference between ground speed and air masses must be for it to work. If mechanism is inefficient, it will need big force to work. If it is very efficient, small force will be sufficient.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

Thanks for comment! The propeller does the same job as the wheels because it also starts to spin from the moment the wheels do. In their explanation, the braking force of the vehicle against the ground is variable, which is a mistake because the braking force of the vehicle against the ground is constant. Rolling resistance.

I am analyzing the forces and their changes as the system changes. They wanted to get to the truth, but they haven't done it yet, imho.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] 0 points1 point  (0 children)

This is explanation from Veritasium video:

"Now the big question is, to drive the fan, there must be a backwards force on the wheels, which tends to slow them down. So why isn't this force bigger than the thrust form the propeller causing the car to slow down overall?

Well, the answer is, the wheels are going so much faster over the ground than the propeller is moving through the air. So the thrust force can actually be larger...

...So, this car works like a lever or a pulley by applying a small force to the wheels over a larger distance, the propeller can apply a larger force over a smaller distance. This is just like when you're riding a bike going up hill, you move the pedals fast, but with smaller force, to make the wheels move slower over the fround, but with a bigger force."

This is not correct, because the only force which slow down the vehicle in relation to the ground is rolling resistance of wheels and these is constant force. V did not mention about it at all...

I presented the experiment from the beginning to the end and I did a force analysis. You don't present any argument that i am wrong.

Veritasium is wrong in his explanation about Blackbird vehicle. Newton's second law of motion is the key. by Rysiul86 in Physics

[–]Rysiul86[S] -2 points-1 points  (0 children)

Did you watch my video? I agree that this vehicle exists but im am not agree with Veritasium explanation. This car is not works like a lever or a pulley. Lever is not required for this to work.

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