Does wind resistance exponentially increase the faster you're going? Like for example the resistance going from 100mph to 200mph isn't 2x but >2x? Wondering because as hp on cars has increased incredibly over the last few decades but speed accomplishments aren't getting all that much faster. Insights?

https://en.wikipedia.org/wiki/Drag_(physics)#Power

Dude just read the drag formula.

Velocity is squared.

That’s why you need only 50hp to get to 50mph but 1000hp to go to 250mph, implying the car has the same drag coefficient and front area.

Another factor in this formula is air density and that’s why long range airplanes fly so high.

The drag is velocity squared but the power to overcome that drag is velocity cubed

Thanks. And I wonder, what does "overcome" mean? Even more than that I wonder the reason for why the force of drag is calculated with squaring the velocity and the power to "overcome" it is cubed...

Overcome means to break through the limiting force of friction at a given velocity. Ie, "to overcome a the drag coefficient at speed x you require y amount of power."

>power to "overcome" it is cubed...

power is torque multiplied by speed. you need squared torque to overcome squared drag force

Overcome is when you jizz in a pussy so hard the cum shoots out everywhere

Are diminishing returns a thing?

I'm not sure, might not be!

tldr; yes

- drag force is linear for slow flows, but is quadratic for fast flows

- for a car sized object in air that change is somewhere in the ranges of 100-200 mph

- this means that changing top speed by 10% requires 20% more force to balance increased drag (110% is a factor of 1.1, square of 1,1 is roughly 1,2, that's 120%)

- as pointed out power output requires an even bigger increase, because power = force * velocity, and since force is proportional to velocity squared, power is proportional to a cube of velocity

- this means that changing top speed by 10% requires at least 33% more powerful engine to balance increased drag

>drag force is linear for slow flows, but is quadratic for fast flows

thats just fricking magic

it's just plain fricking wrong

It's a simplification for sure but it's not "plain fricking wrong"

Or please point out what's wrong, maybe I'm insane or something

The physics are the same at 10 mph as they are at 200 mph, the drag resistance always increases with the square of the speed. There is no magic number where it goes from linear to quadratic. It's just that at lower speeds the rolling resistance is dominant so increases in drag resistance aren't as noticeable, and starting from around 60 mph the drag resistance becomes the dominant factor (depends of course how heavy and aerodynamic your vehicle is).

>The physics are the same at X as they are at Y

anon do you think the drag force is a fundamental law of nature or something?

it's just an approximation

physics are different because the processes are different

at perfectly laminar flow drag is linear period. (see stokes law)

>the drag resistance always increases with the square of the speed

no

apart from the laminar flow mentioned above, the thing is that drag coefficient as used in quadratic drag equation is not constant (why? because frick you that's why, but actually for reasons mentioned above, quadratic equation is just an approximation, it doesn't actually describe the physics of what is happening, despite being derivable from a simplified molecular model, the real processes are much more complex)

up to Reynolds numbers of about 1000 linear drag is a perfectly good approximation because drag coefficient [roughly] linearly decreases with increase of flow velocity (pic related). So it would make sense to instead use a linear equation with another "drag coefficient" which would be constant instead

I was still wrong however, because I grossly miscalculated reynolds number for a car moving at 100 mph :^) lol

kinetic energy is mass multiplied by velocity squared, yes

that is indeed a fundamental law of nature

ok

don't go there anon, you don't have to go there

just for your own sake don't go there it gets nasty

but no this is also just an approximation of classical mechanics

in fact I can't remember if there is any high-school physics formula that is a fundamental law from a modern day physics perspective

Well, two “whys” here:

1-the compressibility of air, at high pressure this will cause changes in the laminar flow that may help or worsen the drag

2-the supersonic transition but cars don’t have to worry about that. Supersonic aerodynamics are very weird, especially in the transitional state.

Also this sphere example can get a lot more complicated if the sphere begins to turn. See Coǎnda effect.

Top speed is when the power output reaches a point where it matches the combined friction losses of the power train and the total combined drag. Much like terminal speed on a fall except you are burning gas instead of potential gravitational energy.

Threads with questions people should have learned in/during/by highschool age and can easily google search should be ignored or reported as spam

>hp on cars has increased incredibly over the last few decades but speed accomplishments aren't getting all that much faster.

The drag force equation was already spoon fed to you so I'll provide this part. Top speed is the most pointless metric, it's why only the only cars setting those records are the most expensive in the world. It doesn't just have to make a bunch of power it has to make that power while passing emissions and noise standards and be able to do it repeatedly without blowing up. Then there's the issue of the tires. The tires on those cars are expensive for a reason. Plus, it doesn't matter if you can afford it, you most likely will never get the opportunity to max it out.

When you are driving there is pressure at the front where the wind meets the car, this is because it takes time for the air to move away so if you go faster you build more pressure. You know how when you pump up a bike tyre and it doubles in resistance really quick right near the end. When you are going really fast you are sort of trying to compress air at the front much more.

You ever go swimming, move your hand through the water, next try to move it much faster, its pretty hard.

its TANGENTAL. 1:4. 400 hp 180mph. 200 needs 550, 220mph needs650hp 240 needs 750, 250 needs 1200, etc. doesnt matter the rubber tyres fail.