Tires
Tires are a key component to move our car and keep it going. For the tire to work, it must use friction on its treads and on the road. The larger the coefficient of friction, the easier it is to accelerate your car. On a dry road, the coefficient of friction is about 0.7, for a wet road it drops down to 0.4 and for snow: 0.1. If you were to think of the tire as a force diagram, the tire must be spinning fast enough to overcome this friction. When you slam on the breaks on a dry road, you'll notice that your tires produce skid marks, but if you do that on an icy day, you'll just slide right along. This is because over ice the tires can't find any friction to grip on to and stop the car.
Let's talk a bit about skid marks. When you slam on the breaks on a dry day, you'll notice your tires will lock up, but sometimes you're still moving. Skid marks can be explained with some simple physics. The force pushing a car along a road is given by f=umg. Where u is the coefficient of friction, m is the mass of the car and g is the acceleration due to gravity. u is determined by the road and the tires of the car. So how long will skid marks be if you know the initial speed of the car? If we consider the car's kinetic energy of KE=(1/2)mv^2 we can relate this to the formula for work. Work, W=(force)*distance. Since the energy from the car's velocity gets transferred to heat and friction when it comes to a complete stop, work is equal to the initial kinetic energy. Putting these together we get W=KE=>umgd=(1/2)mv^2 or distance=(v^2)/2ug If we look at this formula we can see that the faster you're traveling, the longer the skid marks and the longer it takes to come to a complete stop!
Hydroplaning is when your tires lose contact with the road. This usually happens when you are traveling too fast on a wet road and the water gets in the tread of your tires forming a sheet of water between the road and tires. Using the breaks during a hydroplane will not work because the tires have nothing to grip on to to stop. When you do start to hydroplane, the best thing to do is to keep your hands on the wheel and take your foot off the accelerator. Like skidding in the snow, don't use the break. You will eventually slow down enough to regain traction. You can tell if the car ahead of you is hydroplaning by noticing if they aren't spraying up any water or leaving track marks in the water. If they aren't leaving track marks in the water, they aren't actually touching the surface of the road and are hydroplaning.
Let's talk a bit about skid marks. When you slam on the breaks on a dry day, you'll notice your tires will lock up, but sometimes you're still moving. Skid marks can be explained with some simple physics. The force pushing a car along a road is given by f=umg. Where u is the coefficient of friction, m is the mass of the car and g is the acceleration due to gravity. u is determined by the road and the tires of the car. So how long will skid marks be if you know the initial speed of the car? If we consider the car's kinetic energy of KE=(1/2)mv^2 we can relate this to the formula for work. Work, W=(force)*distance. Since the energy from the car's velocity gets transferred to heat and friction when it comes to a complete stop, work is equal to the initial kinetic energy. Putting these together we get W=KE=>umgd=(1/2)mv^2 or distance=(v^2)/2ug If we look at this formula we can see that the faster you're traveling, the longer the skid marks and the longer it takes to come to a complete stop!
Hydroplaning is when your tires lose contact with the road. This usually happens when you are traveling too fast on a wet road and the water gets in the tread of your tires forming a sheet of water between the road and tires. Using the breaks during a hydroplane will not work because the tires have nothing to grip on to to stop. When you do start to hydroplane, the best thing to do is to keep your hands on the wheel and take your foot off the accelerator. Like skidding in the snow, don't use the break. You will eventually slow down enough to regain traction. You can tell if the car ahead of you is hydroplaning by noticing if they aren't spraying up any water or leaving track marks in the water. If they aren't leaving track marks in the water, they aren't actually touching the surface of the road and are hydroplaning.
Here is a fun video from BBC's Top Gear about hydroplaning. Notice how speed and the tire treads add to the effect of hydroplaning. Something else to notice is the depth of water. The deeper the water, the more likely you are to hydroplane. I don't recommend doing this at all with you car!!
Similar to hydroplaning, when you skid on snow your tires lose traction with the road. Just with the snow, the tires are prevented from making contact with the road by a sheet of ice. This slipping can happen at any speed, not just fast speeds. A big problem with slipping on ice, is that sometimes the friction is so low your car can't move anywhere and your tires just spin and spin. Again, if you start to slide, don't use the breaks because your tires will just lock up and you'll lose control of the whole car.
This video, again from BBC's Top Gear, shows what happens when you have a race on a track covered in snow. I want you to pick up on a few things. Notice how much snow the cars have to pick up in order to even start their acceleration, also how sometimes it looks like the wheels are standing still because they're just sliding, and how going too fast will result in getting stuck! Driving in the snow is a whole different strategy.
The most effect way to drive is to always have your tire tread thick enough and to rotate your tires. If you car is front wheel drive, your front tires will wear faster then your back since these tires have to come up with the grip on the road to accelerate the car. (Opposite for rear wheel drive, and all wheel drive wears them all) By rotating the tires, you bring the front tires to the back so they wear more evenly and prolong the life of your tires. The key part to the tires are making sure they have a strong coefficient of friction to grip the road.
The most effect way to drive is to always have your tire tread thick enough and to rotate your tires. If you car is front wheel drive, your front tires will wear faster then your back since these tires have to come up with the grip on the road to accelerate the car. (Opposite for rear wheel drive, and all wheel drive wears them all) By rotating the tires, you bring the front tires to the back so they wear more evenly and prolong the life of your tires. The key part to the tires are making sure they have a strong coefficient of friction to grip the road.
Work Cited
Barksdale, M. (n.d.). HowStuffWorks "What to Do When Hydroplaning".HowStuffWorks. Retrieved July 16, 2014, from http://auto.howstuffworks.com/car-driving-safety/accidents-hazardous-conditions/hydroplaning2.htm
Hokin, S. (n.d.). The Physics of Everyday Stuff - Skidmarks. The Physics of Everyday Stuff - Skidmarks. Retrieved July 16, 2014, from http://www.bsharp.org/physics/skidmarks
Nave, R. (n.d.). Friction and Automobile Tires. Friction and Automobile Tires. Retrieved July 16, 2014, from http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/frictire.html
Barksdale, M. (n.d.). HowStuffWorks "What to Do When Hydroplaning".HowStuffWorks. Retrieved July 16, 2014, from http://auto.howstuffworks.com/car-driving-safety/accidents-hazardous-conditions/hydroplaning2.htm
Hokin, S. (n.d.). The Physics of Everyday Stuff - Skidmarks. The Physics of Everyday Stuff - Skidmarks. Retrieved July 16, 2014, from http://www.bsharp.org/physics/skidmarks
Nave, R. (n.d.). Friction and Automobile Tires. Friction and Automobile Tires. Retrieved July 16, 2014, from http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/frictire.html