Many of us have gotten rock chips, but how many of us understand how those pesky rocks hit our windshield? A common misconception is that the car in front of us throws rocks "backward" and hits the following car's windshield. A rolling tire cannot throw a rock backwards. A tire is a rolling object, thus every point along the tire is moving forwards. There is no force going in a backwards direction. Only direction part of a rolling object can go is a combination of up or down, and forward.
The velocity of the rock at any given point can be determined by adding it's translational velocity at the center of mass (the orange arrow) with it's rotational velocity.
Vrock= Vcenter of mass + Wrock Where V is the translational velocity, and W is the angular velocity
This can be simplified to Vrock=WDR Where D is the distance from the road at the point of contact in terms of R, the Radius. That is to say, that the velocity at the top of the tire would be Vrock=W(2R) =2Vcenter
That is to say, that the rock at the top of the tire may be going twice as fast as car itself. Similarly, at the point of contact of with the road, the velocity of the rock is 0.
So this leaves one to ask, how do those pesky rocks get thrown at a windshield? If it is hit by the following car, then it is because the rock was thrown somewhat vertically, slowed down by air resistance and the car behind it ran into the rock.
It can also be hit by a car going in the opposite direction. The magnitude of this collision will be much greater because it involves objects going in opposing directions. This is why the worse rock chips are often from cars going in the opposite direction, and why it is possible to throw rocks at yourself, which often do not do any damage.
Tires are thrown from tires because the centrifugal force expels snow, rocks, and other foreign objects.
Tire manufacturers sometimes publish a coefficient of rolling friction (CRF) for their tires. You can use this number to calculate how much force it takes to push a tire down the road. The CRF has nothing to do with how much traction the tire has; it is used to calculate the amount of drag or rolling resistance caused by the tires. The CRF is just like any other coefficient of friction: The force required to overcome the friction is equal to the CRF multiplied by the weight on the tire. This table lists typical CRFs for several different types of wheels.
Regardless, of the size of the crack in the windshield you should be worried. Windshields are safety devices that protect against injuries and death. It is essential during car accidents, because it offers a layer of protection. Most trucks now have a disclaimer sign attached to the back. It states that neither the driver nor the company is to be held responsible. This is not entirely true and is meant to discourage people from filing claims. The driver or the company is responsible if dirt, gravel, rock fall off the top of the truck. Admittedly,
The Wanda ATV/UTV tires have a deep tread depth for excellent traction. However, the tread depth is specific for both the rear and front tires. The tires have a tread depth of 20 mm. The front tires have a rim width of 6.5 inches and 370 pounds @ 7 PSI. On the other hand, the rear tires have a rim width or 8 inches and 420 pounds @ 7 PSI.
This image is depicting a rock fall, there are huge boulders on the bottom of the area blocking the road. There is no water so it seems to be a free fall of rocks from the top of this mountain region, and fell to the road on the bottom with the influence of gravity.
“A body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force (Inertia, paragraph 1).” Suppose a car, going 50 M.P.H., hits a pole. The driver would be ejected out of the windshield, due to his body wanting to stay in motion. If that same car were to take a turn too quickly and lose traction, it would continue in the same direction it was going. Before hitting a pole, suppose this same guy set a mug of coffee on the top of his car, while he put air in his tires at the air pump. He then got in his car and drove away, forgetting about the mug. When he finally realized he forgot it, he pulled over to get it, but it was gone. He went back to the air pump to find his shattered mug on the ground. The man later decides to go bowling, so he put a bowling ball in the hatch of his car. He peels out because he is late and suddenly hears a shatter. The man pulls over and sees a bowling ball sized hole in the back windshield. What a smart idea!
Most people though aren't out there trying to lose a tire on purpose. If you're like most people you want to drive on your tires as long as conceivable. But should the unexpected happen some long lonely night and the world seems to want you to simply stare out at the stars on the dark moonless night in the middle of nowhere, it would behoove you to have a slight understanding of the workings of your spare tire, wherever it may be stowed, since cell phones don't always work everywhere. At this point fate might be telling you to slow down. Alas, this isn't usually the case, so give heed, and have some advice.
The average driver doesn’t think about what keeps their car moving or what keeps them on the road, but that’s because they don’t have to. The average driver doesn’t have to worry about having enough downforce to keep them on the road or if they will reach the adhesive limit of their car’s tires around a turn. These are the things are the car designers, professional drivers, racing pit crews, serious sports car owners, and physicist think about. Physics are an important part of every sports and racing car design. The stylish curves and ground effects on sports cars are usually there not just for form but function as well allowing you to go speeds over 140 mph in most serious sports cars and remain on the road and in reasonable control.
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Logan was on his way home from an evening at the local bar. He and some friends had gone out to have a couple beers. As he sped down the road, he blinked vigorously to try to clear his vision. Although it was a perfectly clear summer night, Logan’s vision was blurred from the alcohol. “As long as I keep this car on my side of the road, I’ll be fine,” he thought to himself. He was doing a decent job of obtaining control over the vehicle, or so he thought. Only three miles from his country home, he became unaware of his position on the road as it began to curve. As he continued around the familiar curve in the road, a truck came out of nowhere at hit Logan’s small Toyota Camry head on. The big F-350 pickup truck was no comparison to the little
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