Actually the calculation I'm going to describe is basically the same whatever shape the animal is, but choosing a sphere means I can write down some simple formulae.
The dust and particles from mining roads, stockpiles, and lands disturbed by mining are a significant source of air pollution.
The Mechanics of Strip Mining This section describes the five main types of surface coal mining techniques: Underground mining is also considered in this section. Terrain, economics, and custom generally dictate which technique an operator chooses. All surface or strip mining first removes the overlying vegetation, soil and underground rock layers in order to expose and extract coal from an underground seam or coal deposit.
Responsible surface mining attempts to limit the side effects of this removal through several basic steps: First, the surface vegetation trees, bushes, etc. Next, the operator removes the topsoil, usually by bulldozers or scrapers and loaders.
The operator either stockpiles the topsoil for later use or spreads it over an area that already has been mined. After removing the overburden, the exposed coal seam is usually fractured by blasting. The operator then loads the fractured coal onto trucks or conveyor belts and hauls it away.
Next, the operator dumps the overburden or spoil that was removed during the mining process on a previously mined area and grades and compacts it.
Special handling may be necessary if any of the overburden contains toxic materials, such as acid or alkaline producing materials. Any excess overburden that remains after the mined area is completely backfilled Eastern mines generally have substantial excess spoil is deposited in a fill.
Finally, the operator redistributes the topsoil and seeds and revegetates the mined area. While these basic steps are relatively consistent, the environmental impacts of the five main techniques vary significantly.
Area Mining Area mining is the technique most often employed in the flat or gently rolling countryside of the Midwest and western United States. Area mines excavate large rectangular pits, developed in a series of parallel strips or cuts which may extend several hundred yards in width and more than a mile in length.
Following scalping of the vegetation and topsoil removal, area mining begins with an initial rectangular cut called the box cut. Area strip mining with concurrent reclamation. The operator places spoil from the box cut on the side away from the direction in which mining will progress.
In large mines, huge stripping shovels or draglines remove the overburden. After extracting the coal from the first cut, the operator makes a second, parallel cut.
The operator places the overburden from the second cut into the trench created by the first cut and grades and compacts the spoil. The backfilled pit is then covered with topsoil and seeded.
This process continues along parallel strips of land so long as the ratio between the overburden and the coal seam, called the stripping ratio, makes it economically feasible to recover coal. Mining may cease in a particular area, for example, where the coal seam becomes thinner or where the seam dips further below the surface.
When the operator reaches the last cut, the only spoil remaining to fill this cut is the overburden from the initial or box cut. Yet, since the box cut spoil may lie several miles from the last cut, the operator generally finds it cheaper not to truck the box cut spoil to the last cut.
Instead, he may decide to establish a permanent water impoundment in the last cut. These last cut lakes are commonplace in the coal regions of the Midwest but may pose environmental and land use problems. A later section of this handbook describes strategies for challenging these last cut lakes.
Open Pit Mining Open pit mining is similar to area mining. The technique is common in the western United States and other parts of the world where very thick — 50 to foot — coal seams exist. Open pit mines are usually large operations.
Production levels may exceed 10 million tons of coal per year. The thick coal seams found at these large mines ensure that the amount of land disturbed for each ton of coal produced is much smaller than for most Eastern and Midwestern mines.
Nonetheless, the sheer size and capacity of these mines necessitates substantial surface disturbance. In open pit mining, the operator first removes the overburden to uncover the coal seam.
The overburden may be placed on adjacent, undisturbed land, or it may be transported by belt or rail to the other end of the same mine or to an exhausted mine that needs to be backfilled.May 05, · The amount of drag generated by an object depends on the size of the object.
Drag is an aerodynamic force and therefore depends on the pressure variation of the air around the body as it moves through the air. The total aerodynamic force is equal to the pressure times the surface area around the body.
Drag is the component of this force along the flight direction. The x W() equation (where W = weight in kilograms) used to estimate body surface area (SA) in cattle energy requirements models was developed using measurements of sheep that weighed. Although a larger area of contact between two surfaces would create a larger source of frictional forces, it also reduces the pressure between the two surfaces for a given force holding them together.
Since pressure equals force divided by the area of contact, it works out that the increase in. The normal force is always directed perpendicular to the surface, and the friction force is always directed parallel to the surface. F F and F N are always perpendicular to each other.
The force due to friction is generally independent of the contact area between the two surfaces. The surface area affects evaporation because if more area is exposed to air, allowing water molecules acquire more heat energy from the surroundings.
Due to the increased heat energy (kinetic energy), there is more rapid movement of the water molecules which . Lab Report = Surface area to volume ratio effect on diffusion. 13 Pages. Lab Report = Surface area to volume ratio effect on diffusion or download with email.
Lab Report = Surface area to volume ratio effect on diffusion. Download. Lab Report = Surface area to volume ratio effect on diffusion LAB REPORT Research .