Car in a windtunnel!

[zasca]

Whoa people! Have we all forgotten about the traction of the tires as a factor?!?!?! And provided enough wind, I can make the car fly too... Think of the children (in the back seat)!!!!!!!!!!!!!!!!

 

[flyf15]

*sigh*

Whoever first thought of this treadmill thing needs to be punched in the face.

 

[joe_pilot]

If you don't understand F = MA , then you don't understand cars or airplanes.

Oh, I see. You are one of THOSE people. You know. One of those people who think everyday things in the physical world can be explained by Newtonian Physics. Just what kind of a whack-job are you anyway?

We all know that they both work because of...

...Chemtrails.

-JP

 

[dash8driver]

F = MA

Consider the net horizontal force acting on vehicle in the tunnel. In the first instance of time wheels apply a force F0 along the horizontal axis in an attempt to accelerate the vehicle.

But the tunnel, following its imperative, applies enough wind in the opposite direction to cause a drag force equal to the force being applied by the wheels. No matter how hard the vehicle tries to accelerate, the wind speed increases sufficently to equal the force provided by the vehicles drive train.

If the vehicle is an airplane it will lift off at the normal airspeed (groundspeed would be zero), but if its a car it will just stay there, just as if it were hard up again a brick wall.

If you don't understand F = MA , then you don't understand cars or airplanes.

remember, the treadmill is only increasing the wind SPEED at the same rate as the car is increasing its speed.. its not increasing the wind speed to equal the force of the car...that would require a much greater wind speed than the car's speed which would violate the rules for the wind tunnel in this test. lets break down the equation:

F = M * A

because the air is accelerating at the same speed as the the car, A in this equation is going to be the same for both the car and the air.

the mass of the car is significantly more than the mass of the air therefor F(car) is going to be much greater than F(air). since F(car) is greater than F(air), the car will move forward.

as long as the wind tunnel is doing what its supposed to do, increasing the wind speed at the same rate as the car, the only way for the force to be equal is for the mass of the air to be the same as that of the car.. i'm not sure how to do that. otherwise the speed of the air would have to increase significantly in order to compensate for the difference in M... and that's not how this wind tunnel works.

 

[medfly]

What's pulling the treadmill?

Is another call pulling the treadmill?

 

[dash8driver]

whoops.. replace "treadmill" with "wind tunnel"

 

[JimNtexas]

remember, the treadmill is only increasing the wind SPEED at the same rate as the car is increasing its speed.. its not increasing the wind speed to equal the force of the car...that would require a much greater wind speed than the car's speed which would violate the rules for the wind tunnel in this test. lets break down the equation:

F = M * A

because the air is accelerating at the same speed as the the car, A in this equation is going to be the same for both the car and the air.

the mass of the car is significantly more than the mass of the air therefor F(car) is going to be much greater than F(air). since F(car) is greater than F(air), the car will move forward.

as long as the wind tunnel is doing what its supposed to do, increasing the wind speed at the same rate as the car, the only way for the force to be equal is for the mass of the air to be the same as that of the car.. i'm not sure how to do that. otherwise the speed of the air would have to increase significantly in order to compensate for the difference in M... and that's not how this wind tunnel works.

You're right, if our hypothetical wind tunnel just equals the speed of the car, then it is as if the car is driving into a 60mph headwind at 60mph, something that's clearly possible.

That just strikes me as lame. MY wind tunnel is going to instantly generate enough wind to hold the car in place, which of course will require a much greater windspeed than the speed the car would attain at a given power setting.