19 Oktober 2012

Friction and Its Application

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In our daily life, we always encounter with friction. It arise when two or more things make contact one another and has direction opposing to relative motion of the things or if the things have no relative motion, the direction of the friction will oppose to tends of motion of the things that contact.

For instances, imagine a block lay on a inclined plane. The question arises in our mind then is why the block is still unmoving? It should move down along the inclined, shouldn’t? Well, if there is nothing visible that cause the block to still, for instances rope tight to the block, then there should be a friction that keep the block stay still on the inclined plane. Because the unmoving thing tends to move down along inclined plane, then the direction of friction is upward along the inclined plane. If it turns out the block moves upward due to pushing then the direction of friction will be downward opposing to the direction the motion of the block.

The presence of friction in everyday life, besides raise us a negative impact, it also has a positive impact. God always create everythings in this world has two aspects: their beneficial and detrimental aspects. In many cases, the presence of friction may disadvantages us, because it will cause our engine components quickly wear when rotating, our motorcycle’s tires will quickly bald so we have to spend some payment to replace it, and so on. But imagine if friction is absent. How can we walk on the way? How can we ride our motorcycle on the road? How can our fingers pressing computer keys to type word by word that build up this article?
The disadvantages of thing are actually created by God just for our benefit, as in the case of frictional force. We will discuss how to apply this friction force in our daily life that is how to apply it in designing a road, mainly a curved road.

A road at some place is impossible made straightly on. There are some moments when roads must be curved. Moreover, if the topography of the areas is hilly areas. In such cases, it is not possible to make a straight way upward. Instead, the road should be made curve.

One of many curved road in South Sulawesi. For the safety of rider, it should be fitted with road-markings to alert the rider or driver. Road markings should be eye-catching. For this reason, it should be made and designed professionally. There are many professional road sign makers who can help us if we cannot make and design it ourselves.

Imagine you are driving a motorcycle and start to entering a bend way. Here, even if you have never studied physics before, but actually you have applied a number of principles of physics. Firstly, you have to reduce your vehicle speed. If not so, then you do not care about the law of inertia and this means you threaten your life.

The law of inertia (Newton's first Law) suggested that if there are no certain causes, the body tends to retain its original state. At first you move straight into a certain direction, and then suddenly have to cornering. But due to inertia, you together with your motorcycle will tend to keep moving straight ahead without caring that in front of you is a ravine. There must be a cause for you to follow the trajectory that will be curved. And the cause is friction. So, that friction that usually raise some disadvantages actually has saved your life in this case. When you turn the handlebars or the steering wheel of your vehicle in a particular direction, it just helps steer the vehicle to follow the path bends. It was the friction that the main hero for you. Without this friction, no matter how you turn the steering wheel, your vehicle will continue to slide into the ravine!

But why should we slow down the speed of our vehicle?

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When you are move on the curved way, the centripetal force act on you. This centripetal force attract you toward the center of curvature of the bend way and this centripetal force is supplied by friction. Since the centripetal force is proportional to the square of the velocity, it means that the greater the speed, the greater the centripetal force that you experience. Since the friction force is actually act on the surface of the contact between your bike’s tires with road, and because the system (you together with your bike) is a rigid body, then the existence of this friction force actually could also cause you to twist (undergo a rotational motion. Rotational motion such as this case usually we can see when the rider who had an accident due to a high velocity during cornering). Therefore, to avoid this undesired incident, you should reduce your speed. By reducing your speed, the friction force that will cause torsion is also reduced so that you can anticipate the undesired twisting by tilting your body so that the torque due to friction force offset by your body and motorcycle’s weight.

Now it is clear that the friction is very helpful to us here. But there are other problems. Our vehicle’s tires wear faster when we go on the curved road. So, could we turn without relying too much to friction force so that our motorcycle’s tires will be durable and our safety keeps maintained? To reduce the influence of the friction force on the bend road, it is usually inclined with a certain angle. It is meant that the normal force act to us due to road surface has a component in the direction of the center of the bend curvature. In this case, in addition to the friction force, the component of normal force will also contribute to the centripetal force so will reduce the duty of the force of friction. As a next result, the friction between the tire and the road surface is much smaller so the tires will be more durable. But even so, the most important way in order to avoid undesired accident in driving a vehicle on the road, especially on the curved road is circumspection. Although the curved road has been tilted, we still have to notice that there is still a certain speed limit must be followed by the driver to maintain the tire durability as economic considerations and of course the safety considerations. You may see some example of good and nice road sign here. Therefore, at every turn, it should be installed road markings to remind riders or drivers, which includes how much the optimal speed of vehicles permit on the road. Road markings should be eye-catching, and easily understood by the driver or rider who are in moving but without distract their concentration too much in order to preserve their safety. For this reason, road markings should be professionally designed by road sign manufacturer.

3 komentar :

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