Become a fan of Slashdot on Facebook

 



Forgot your password?
typodupeerror

Comment Re:Drag force, coefficient of drag negative? (Score 1) 200

I can only suggest to watch the first video I linked again. You can see the cart is going forward faster than the bar hold by Derek.

I think the analogy is correct, but in the case of the wind is a bit more complicated. When the vehicle is still, the wind push it forward. Now the wheels are connected to the propeller through a gear box, with a right ratio so the propeller rotate fast enough to push the vehicle further and not too much because the force will be too weak to go against the inevitable resistance (friction, air and so on).

Sorry if I can't explain better than this...

Comment Re:Drag force, coefficient of drag negative? (Score 1) 200

Not at all. It's a lever that multiply the current drag. With no wind, no drag, and 0 multiply by any number is still zero.

And like in any mechanical lever (like also in a gearbox) you can multiply the drag, but you decrease the force and so the acceleration. And I haven't take in account friction in account yet.

If you consider the friction at certain point increasing the multiply factor, you also reduce the force below the friction force and you get no increased drag anymore.

Like in the first video linked, when you don't push the bar, the car don't move at all, when you push the bar, the car move forward by a ration equal the ration of the wheels. No magic involved.

Comment Re:Drag force, coefficient of drag negative? (Score 1) 200

You have to watch the second video for a better explanation. TL;DW: the wind push the car, the moving forward respect the ground make the wheel spin, the wheel spin make the propeller push air behind, ??, profit :)

Seriusly, it's a sort of lever, that multiply the push of the wind.

Take a look at this: https://youtu.be/yCsgoLc_fzI?t...

And I also recommend this video: https://www.youtube.com/watch?... for another explaination

Comment compression (Score 1) 118

logitech dropped mpeg compression? I'm not sure, at least you need some kind of compression if you want to have more than 640x480 at 30fps, because the bandwitdh of usb 2.0 it's quite limited.

And I have a cheap usb chinese 1080 camera that supports mpeg streaming.

Slashdot Top Deals

"Little prigs and three-quarter madmen may have the conceit that the laws of nature are constantly broken for their sakes." -- Friedrich Nietzsche

Working...