in films car rims  look as if they where rolling backwards why?
609168
Excellent question!\n\nBecause film is composed of 25 frames per second the much-faster revolution of the holes in the wheel rim gets out of phase.
498394
You have a bevel gear on the end of the drive shaft (the input shaft to the differential). This gear right-angle drives a large "planetary" or ring gear that rotates about the axle but is not attached to it directly, but is attached via a yoke that carries two intermediate bevel gears, and these gears mesh with the gears that drive the two wheels. (You really need to look at the ref.) When the two wheels want to rotate at the same speed, the two bevel gears do not need to rotate and the transmission acts like a simple nondifferential mechanism. However any differential motion of the wheels is accommodated by rotation of the intermediate gears.\nP.S. For some reason I had to go to another page (at the ref. website) and then back to get the animations to work right.
18257
you were correct.  It appears that the howstuffworks diagram showing the bicycle mentioned in another answer is in error in that the bicycle would be upside down as shown but the tires and handlebars should not be reversed the way shown.  For example if you are looking at a nearby shrub and a distant tree, both would be upsidedown on your retina.  But the order of objects would be tree, shrub, focal point of eye, shrub image then tree image.\n\nAn experiment was conducted where people wore special glasses that inverted objects as the eye does.  After a while they learned to see correctly again and when they took the glasses off everything was inverted until they re-learned to see correctly once again.
844700
Mostly for easy acces in and out of the car, also the wheel is marked showing the center of the wheel to the steering colum.  If something should knock out the alinment the driver can compensate by removing the wheel and turn it left or right so the steering is center again.
438273
the tires pop like heck\njkjkjkjk\ni don't really kno
1057048
Put stupid looking rims on my car!
338364
Wagon wheel effect read about it at http://en.wikipedia.org/wiki/Reverse_rotation_effect
1134357
because the wheels are pushing back at the ground, the ground in turn pushes the car
312531
Wheel alignment is how aligned wheels are with respect to each other. For example, you wouldnt want your front wheels to point away from each other.... they would rub themselves off as they rolled.  \n\nWheel balancing is balancing the weight of the wheel on its center. If one side of a tire was to weigh a few ounces heavier then the other side, it would vibrate when you drive at higher speeds.\n\nJust take your car to a repair shop.
449007
It's not a gimmick, it's an illusion , the same as the mtatlic hill, you're going down but it looks lie uoi are going backwards,something to do with physics, ask the physic' pro's for the deep, lengthy answer, they're good!
444984
My bottom shaped car is a work of art! Any car (be it pink with a penis shaped gearstick, or penis-shaped with a pink gearstick) would be very excited by my car. And if I really squeeze (on the brakes) it leaves skid marks....
458532
This effect is called aliasing.  It happens whenever the sample rate falls below twice the rate of rotation of the tires.  Imagine a tire with a marker on the top (at rest) and start spinning it 1 time a second. Also imagine you are taking pictures of it every 3/4 of a second.  The first picture, the mark will appear at the 3/4 position around.  The second picture, the mark will apear at the 1/2 position, then the 1/4, and so on.  When you play them back, the tire will appear to spinning backwards.
957446
Molecules are slowed down when it is cold therefore they contract and therefore the tire looks low. When its heated back up it will return to prior state
527159
It's due to the way in which your eyes percieve light. Focus is determined by a point of reference. If your friend that you are looking at is the point of reference, they will appear as if they are not moving.\n\nThis is similar to when it looks, in a car, as if you are going backwards when the truck next to you starts moving forward.
1060039
so that they roll. why are wheels round?
1132800
Cuz that's how they roll
149524
Think of how animation works.  You see a picture, then a short time later, you see a slightly different one.  If the time between pictures is short enough, your brain interprets this as a moving picture.  (Why your brain does this has traditionally been attributed to the phenomenon of "persistence of vision", but it is likely much more complicated than that."  )  \n\nNow imagine a tire (sorry, I'm American, so I'll stick to our spelling) that has a white letter M (for Michelin) on it's sidewall.  The tire is spinning, so the letter M moves in a cirle, so that you see the white M at the top of the circle, then a short time later see it at the top of the circle, then a short time later at the top of the circle again, etc.  Because of the way the brain processes information, at a certain speed the brain will interpret this successive sightings of the M at the top of the circle as the M remaining stationary.  \n\nNow imagine the tire spinning a little slower, so that the M doesn't quite make it all the way around the circle before it is perceived again. The M started at the top of the circle, then the next time it was perceived it was located at say 11 o'clock, then the next time at  10 o'clock, etc.  Now, your brain will interpret the succesive pictures of the M as the M moving backwards.\n\nThis effect is even more pronounced in movies and TV, where the technology forces us to see motion split up into successive frames.  It is also the principle behind the timing light used to tune auto engines, for example.  A light that strobes on and off at a set frequency allows the mechanic to determine how fast the engine is turning by observing the motion, and adjusting the frequency so that the engine appears to be motionless.