Air Resistance, Tyres And Friction Essays - Classical Mechanics

Air Resistance, Tyres and Friction Blake Smith Dragsters use a combination of large wide tyres or the rear and small narrow tyres on the front this combination is used for the following reasons: The front wheels: The front wheels are very narrow. This is so a minimum of air resistance or drag affects the dragster with lower drag better acceleration an in turn a better top speed can be achieved all leading to a better pass (race time). Now lets try to understand the concept of air resistance and drag. A basic example is placing your hand out the window with your palm facing forwards as you are driving your car along at about sixty kilometres per hour. You will feel a strong force of the wind (air resistance) pushing back at your hand. Now turn your hand side or so that your little finger is facing the front and your thumb is facing the rear at the same speed. The force of air resistance exerted on your hand is greatly reduced. This force is similar as to that exerted on the front wheels of the dragster. Now dragsters reach speeds of up to five hundred kilometres per hour, imagine the force needed to hold your hand against the wind if your palm was facing the front. It would be much easier to hold your hand side on. The same as it would be much easier for the dragsters engine to push the narrow front wheels compared to large ones. Air resistance is a form of friction (namely fluid friction) a friction from the air, as we know friction is defined as a force that opposes movement. The formula used to determine aerodynamic drag is as follows: Drag = 0.5 * rho * Cd * v2 * S Aerodynamic drag is a function of the following: - rho is the air density, which we cannot change. - v2 is velocity squared which is endeavoured to be maximized for the best time and/or pass. - S is the frontal or cross sectional area which we want to minimize. I.e. less frontal area means that a less significant amount of air resistance impedes the top speed and acceleration. - Cd is the coefficient of drag, which we want to minimize. So the two things with which can be worked with or changed, the frontal area and coefficient of drag, both of which need to be to minimized for the best results. Having very narrow front wheels minimizes the frontal area. This is the main reason why narrow front wheels are used. If the smaller the wheel the lower the drag, why not have the wheels narrow and very short as well? You ask. Well the reason is that if the wheels were very small they would drop into all the bumps and cause a loss of speed not to mention control. As the wheels would bounce into the depression and then launch up into the air as they come out of the bump. This is extremely dangerous in that the driver can no longer steer the vehicle that is travelling at near five hundred kilometres per hour, the car can also get air flowing underneath the car, with the effect of air resistance the car will lift up of the ground and flip through the air. Also the rotational force is much harder on the bearings causing more wear and friction meaning slower times. Large wheels are used because they will skim over the bumps and keep the car moving along a flat plane. They also exert less force on the bearings meaning less friction and better times. Now if drag cars use narrow front wheels so they can get less air resistance and a better top speed why don?t all racing vehicles run narrow front wheels? The answer is friction. The front wheels of drag cars do not have high cornering or driving force travelling trough them. I.e. they are only there to hold the front of the car up and allow it to roll along the road. In conventional racecars high forces are exerted on the tyre in the horizontal plane meaning that they need to have a good tread area so that they grip the road well and hold the car on the track so it does not slide off

Government and Non-Profit Organizations Essay Example | Topics and Well Written Essays - 250 words

Government and Non-Profit Organizations - Essay Example This will not only provide joint support but will initiate some other ways of improving tourism among the youths and the local people. Some of the governmental agencies which the organization can partner with include Ministry of sports and youth affairs, Ministry of tourism, as well as institutions of higher learning in Kenya. The above mentioned government agencies will be highly meaningful in giving support to the realization of the organization goal in various ways. Ministry of sports and youth affairs is in charge of sporting activities in the country as well as establishing the well-being of youths in the country. It therefore has the influence of youths towards visiting the parks. Ministry of tourism is in charge of promoting tourism in the national and international arena. This will provide an avenue for marketing the organization and formulating policies to the local people as well as to the youths hence creating awareness (Jones, 2005). Institutions of higher learning comprising of universities and middle colleges can arrange tour activities such as picnics and adventures to the Nairobi National Park as they are the centre of excellence where many youths are. Despite the efforts by Nairobi National Park to increase the number of local tourist, there are perceived conflicts which are to arise as it partners with government and other agencies. One of the potential conflicts is on the fee to be charged in the entrance. Most young adults do not have enough money to cater for the higher fees charged hence will conflict with the agencies which may introduce small fees. Additionally, the agencies may want to dominate through imposing policies against the organization. The clash in polices will pose a conflict between the organization and government

Nutrition - Ask and Answer - Characteristics of Life Essay

Nutrition - Ask and Answer - Characteristics of Life - Essay Example The following hypotheses were formulated: First, simple obesity among children is affected by the following environmental factors: educational levels of parents, familial inclination to obesity, and other health patterns. Secondly, a diet with low energy component and low glycemic index results into body mass loss. Thirdly, dietary treatment will involve change in the body mass, reduction in skin thickness and adipose folds, scapula, BMI, body fat content and waist hip ratio. Lastly, administration of dietary treatment will affect biochemical indicators like lipid profiles (Rozwoj, 2006). A sample size of 236 children with known simple obesity from Mazowsze region was used. The research was carried out by Gastroentorogical and Endocrinological Unit of the Institute of Mother and Child for10 weeks. Nutritional state was analyzed on the principle of investigating. Eight essential features and five anthropometric parameters were used besides common biochemical indicators for carbohydrate and fat metabolism. Evaluation was done prior to and after the commencement of the study. Studies were carried out on nutrition that comprised eating habits, composition of food, and the constituent nutritional content of food given daily covering a period of 10-14 for every child prior to the dietary treatment and 3 random days after. Collection of data on environmental factors was administered by a questionnaire (Rozwoj, 2006). It was found that environmental factors constituted major risk to obesity. A relationship was established between a normalized BMI z-score with respect to environmental factors which included paternal obesity (Chi (2) test with p-value less than 0.05). Also a positive correlation was found between relative BMI z-score and the anthropometrical factors. No distortions in carbohydrate metabolism were established except for fats (Rozwoj, 2006). The dietary treatment contained