How Tires Work
How it works
they are not really round. There is a flat spot on the bottom where the tire meets the road. This flat spot is called the contact patch. This helps the tire have more space on the ground so that the square inch area touching the ground is higher. By doing this, You don't need as much pressure in the tire. Tires usually only need 30 pounds per square inch. You can figure out how much four tires can hold by adding the square inches touching the ground and multiplying it by four (all tires). Then you must add in the area pressure of all the tires. You find this by finding the area of the tire in square inches and multiplying that by 30.
Related equations
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.
Tire Type Coefficient of Rolling Friction
Low-Rolling Resistance Car Tire 0.006-0.01
Ordinary Car Tire 0.015
Truck Tire 0.006-0.01
Train Wheel 0.001
Let's figure out how much force a typical car might use to push its tires down the road. Let's say our car weighs 4,000 pounds (1814.369 kg), and the tires have a CRF of 0.015. The force is equal to 4,000 x 0.015, which equals 60 pounds (27.215 kg). Now let's figure out how much power that is. If you've read the How Stuff Works article How Force, Torque, Power and Energy Work, you know that power is equal to force times speed. So the amount of power used by the tires depends on how fast the car is going. At 75 mph (120.7 kph), the tires are using 12 horsepower, and at 55 mph (88.513 kph) they use 8.8 horsepower. All of that power is turning into heat. Most of it goes into the tires, but some of it goes into the road (the road actually bends a little when the car drives over it).
A pit crew consists of two tire-carriers (front and rear), two tire-changers (front and rear), a jackman and a gasman. The rear tire changer Removes and replaces the right rear tire, using an air-powered impact wrench on the five lug nuts. He then moves to the opposite side of the car to change the left rear tire. The rear tire changer assists the rear tire changer by handing him a new tire that he's carried from behind the pit wall. He may also adjust the rear shock/jack bolt to adjust a car's handling then move to the other side to carry the other rear tire. The front tire changer and tire carrier does the same thing as the rear just on the front of the car. The jack man operates a 20-pound hydraulic jack that raises the car for tire changes. After new tires are first bolted to the right side of the car, the jackman drops the car to the ground and repeats the process on the left side. The gas man empties two 12-gallon dump cans, which weigh 81 pounds each, into the car's fuel cell. The Pit crew does all of this in under 13 seconds which is about the time it takes for one NFL play or how long it takes for you to walk to the fridge to get another beer. In an autopsy of the pit stop done by Sport Science they broke down the pit stop: The jack man gets to the car and has to precisely center the jack under a ¾ inch bolt raising the car before the tire changer removes all five lug nuts in about one second then tightening the new lug nuts in about the same speed. The entire crew explodes to the other side of the car to do the same to the driver’s side of the car. The gas man empties all 12 gallons of fuel in about five seconds. Just to put into comparison if you have ever changed a tire on the side of the road or even had the luxury of working in a shop it takes much longer to change one tire than these crews take to change all the tires and fuel up
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
While changing a flat tire may seem to be simple enough, there are some safety tips you should know first.
If you find yourself in a situation that requires you to change a tire, then you should refer to this simple nine step guide. Imagine you’re driving down the road and you hear a loud popping noise followed by a slight loss of control of your vehicle. You know in the back of your mind that you’ve blown a tire, but you don’t want to admit it, you’re in denial. You pull over the car and check your tires, you see the flat tire on the driver side of your car right away, your mind spirals into panic. Your palms are sweaty and you’re too embarrassed to ask for help, you don’t know what to do. Then you pull out your phone and Google How to Change a Tire, the first result is from Sean Classen, the world renowned how to writer. After thoroughly reading through the guide you know that you’re set, and confident.
The following steps are the safest way to change a flat tire. If you received a flat tire while driving down the road; first thing to do is to get away from oncoming traffic; at that time, find a place that is well lit, such as a parking lot. Keep in mind the farther you drive on a flat tire, the more damage you will incur to the tire and wheel. Secondly, set the parking brake so that the car does not roll away while the car is off the ground. Then, you have to locate your spare tire, which will replace the flat tire; that is usually in a compartment inside the trunk. The spare tire is secured in place by a bolt or a bracket that unscrews easily. In addition to the spare tire, you will need a jack to raise the car off the ground. The third item you need, is a lug nut wrench that will remove the lug nuts. Place all of the items near the work area. If you have a tarp, lay it on the ground and put some rocks on each corner of it so that the wind will not lift it up off the ground. The tarp gives you something to kneel on; instead, of kneeling on the ground...
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There aren't too many things in life which are more annoying than a flat tire when you least expect it, but then again who really expects a flat. Maybe the bloke driving around on four bald tires is expecting one, but he probably doesn't want one either. Although I will admit that one day on my way to get new tires I tried, and successfully I might add, to "burn off" a tire. Luckily for me though I was within one block of the tire shop, and even more serendipitously the police never caught me on the way there since I would stop for every red light and stop sign only to "light up" the rear wheels upon take off, sometimes reaching 75mph on the speedometer before the tires started to catch and I would end up at a simple slow 30mph.
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If the purpose of brakes is to convert kinetic energy into heat, then in order to know how much heat the brakes make requires that we find out how much kinetic energy there is in a moving bicycle.
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Regardless if one is riding on hard solid pavement or soft dirt, the same basics of cont...
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