Tutor profile: Gautam B.
How Does a Match Light?
Match heads are made using phosphorus - a highly combustible element - that catches fire due to the friction caused when striking the match. Safety matches are slightly different. They will only light if you strike them using the surface on the side of the box. In this case, the match head contains potassium chlorate - an accelerant that speeds up the reaction. The rough side of the box contains most of the phosphorus. Bring the two together and add the heat generated by friction, and you have a flame. Waterproof matches have a thin coating of wax over the whole match. This is removed when striking the head against the box, exposing the phosphorus. This allows the match to catch. To give you enough time to move the match to whatever you wish to light, most matchsticks are treated with paraffin (candle wax).
Subject: Mechanical Engineering
Why is stress considered important in a shaft?
The following types of stresses are prevalent in shafts: > At the outermost surface of the shaft the max shear stress occurs on the cross-section of the shaft. > At the surface of the shaft on the longitudinal planes through the axis of the shaft the maximum longitudinal shear stress occurs. > At 45 degrees to the maximum shearing stress planes at the surface of the shafts the major principal stress occurs. It equals the max shear stress on the cross section of the shaft. > For certain materials where the tensile and compressive strengths are lower in measure as compared to the shear strength, then the shaft designing should be carried out for the lowest strengths. > All these stresses are of significance as they play a role in governing the failure of the shaft. All theses stresses get generated simultaneously and hence should be considered for designing purposes
What is a bearing? What are the different types of bearings?
The bearing is a device that helps smoother movement with minimal friction which in turn helps enhances efficiency and speed. Considering two types of loading, radial, and thrust, there are different types of bearings which help handle these loads. The basic difference in the types of loads is essentially due to their ability to handle the weight and different kinds of loads for various applications. Different types of bearings are: -Ball bearing -Roller bearing -Ball Thrust bearing -Roller thrust bearing -Tapered roller bearing -Magnetic bearings -Giant Roller Bearing
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