Physics Puzzle
- Thread starter Softus
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the OP said something that is impossible.
You have no idea what is the same or otherwise as the question has not specified this.
RPM has certainly not been specified.
So as for (EXACTLY THE SAME) speed in motion from say a fixed point on the ground in a certain direction then yes, this is entirely possible.
You have picked up on a silly flaw in the question to support your pedantic argument but the plain fact remains that THE AIRPLANE WILL TAKE OFF.
As Mythbusters have proven beyond doubt.
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It depends on how you read it.
If you can't read what the OP has wrote thats not my problem.
The speeds are equal, the same, not the wheels going faster to reach take off speed.
Whether its possible or the question is flawed is irrelevant, for the sake of this topic you must assume it happened.
The plane will not take off
I don't need to.
All the time the wheels and the conveyors speeds are equal, then you have two equal opposing forces, therefor the plane will not move.
You are still thinking what is and isn't possible.
Had I been the pilot in the video I would have been most surprised not to take off. but that is irrelevant as well, the plane outran the belt speed, and when you consider the drag on the belt its no surprise
Diyitall wrote
You can't.
Equal in rpm or equal in relation to motion in opposing directions from a fixed point ?.
Complete tripe. You have yet to define these forces and you have purposefully left out the greatest force of all which is the thrust from the engines.
I only know what is possible and knew this before looking at the video.
Then why are you arguing ?
You have no idea what speeds were recorded in the video or indeed what speed you are talking about.
In short you are guessing.
You have also no idea what drag forces were imposed on the conveyor in the video so again you are guessing.
And guessers in my book are ********.
.
You can't.
Equal in rpm or equal in relation to motion in opposing directions from a fixed point ?.
Complete tripe. You have yet to define these forces and you have purposefully left out the greatest force of all which is the thrust from the engines.
I only know what is possible and knew this before looking at the video.
Then why are you arguing ?
You have no idea what speeds were recorded in the video or indeed what speed you are talking about.
In short you are guessing.
You have also no idea what drag forces were imposed on the conveyor in the video so again you are guessing.
And guessers in my book are ********.
The wheels and the conveyor are equal there is nothing to prove.
The plane in the video outran the em !!! mat by 85knots which is the take off speed for that plane.
Why am I arguing, because the video is not the same situation as the topic, they are talking air speed not the wheel speed.
A. the weight of the plane is not supported by the mat, but the ground under it.
B. the mat is trapped between the wheels and the ground.
C. the wheels were faster than the mat, so the plane was able to gain forward momentum.
D. could you see the mat moving and if so how fast, why didn't they paint chevrons on the mat, to compare speeds
The plane in the video outran the em !!! mat by 85knots which is the take off speed for that plane.
Why am I arguing, because the video is not the same situation as the topic, they are talking air speed not the wheel speed.
A. the weight of the plane is not supported by the mat, but the ground under it.
B. the mat is trapped between the wheels and the ground.
C. the wheels were faster than the mat, so the plane was able to gain forward momentum.
D. could you see the mat moving and if so how fast, why didn't they paint chevrons on the mat, to compare speeds
Doitall wrote
Only in your mind they are.
You have still no idea how the speed of the conveyor is defined so therefore you are guessing again.
And the wheel speed (rpm) is irellevant in both cases.
No different from a conveyor. It must have support also. You can use the ground as Mythbusters did or use a purpose built machine with a dedicated friction slip support.
Correct. No different either from the mat on a dedicated conveyor.
You can engineer in slip membranes or friction pads on either.
Now we are getting somewhere.
So you are not talking about rpm but rather motion from a fixed point.
And this is exactly what happens in relation to the OP's question when you define speed as motion from a fixed point.
The speeds can be exactly equal with the correct control system. The speed of the mat (conveyor) being precisely controlled to match the speed of the accelerating airplane due to the thrust.
As the airplane accelerates the conveyor accelerates accordingly with the wheel rpm increasing to make up the difference.
Only in your mind they are.
You have still no idea how the speed of the conveyor is defined so therefore you are guessing again.
And the wheel speed (rpm) is irellevant in both cases.
No different from a conveyor. It must have support also. You can use the ground as Mythbusters did or use a purpose built machine with a dedicated friction slip support.
Correct. No different either from the mat on a dedicated conveyor.
You can engineer in slip membranes or friction pads on either.
Now we are getting somewhere.
So you are not talking about rpm but rather motion from a fixed point.
And this is exactly what happens in relation to the OP's question when you define speed as motion from a fixed point.
The speeds can be exactly equal with the correct control system. The speed of the mat (conveyor) being precisely controlled to match the speed of the accelerating airplane due to the thrust.
As the airplane accelerates the conveyor accelerates accordingly with the wheel rpm increasing to make up the difference.
If you can't understand what that says and the implications balski tough.
If I stand the trolley on the belt it will travel unaided to the end, and the wheels won't turn, that is a positive force.
If I then add a negative force/thrust that is equal to the speed of the belt then I can stop the trolley moving, the wheels are now turning at the same speed as the belt.
Do I really need to say any more
RPM is a measure of rotational speed. I don't think it is right to start using rpm to define 'wheel speed' in this discussion.
You have purposefully left out the part in the question which says..........
The pilot begins to add thrust to the engines...
This thrust is not defined but most sensible people will realise that this thrust will quickly overcome the friction caused by the soft wheels on the surface as Spacecat explained earlier.
However in the case of the OP's question we have a control system which is equalising both speeds.
This simply means that as the pilot applies thrust the airplane accelerates forward and a fixed point on the conveyor accelerates in the opposite direction at precisely the same speed.
And blondini is correct of course to point out that rpm is not relevant to this discussion other than the simple fact that the rpm of the wheels rotational speed will be much higher when the airplane takes off on the conveyor .
Thrust, friction, jet or battery powered it's irrelevant to the topic
The trolley is being held on the belt and the wheels are turning at the same speed as the belt.
The trolley cannot move forward unless the wheels are faster than the belt.
The trolley is being held on the belt and the wheels are turning at the same speed as the belt.
The trolley cannot move forward unless the wheels are faster than the belt.
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