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Thermal Effect

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Thermal Effect THERMAL EFFECT Topic covered Friction Thermodynamics Heat Description Learn how friction causes a material to heat up and melt. What happens on an atomic level when you rub two objects together? Objectives The following can be learned from this simulation: Explain a model for friction a molecular level. Identify what happens on an atomic level when you rub two objects together. Find how friction causes a material to heat up. Instructions Rub the yellow atoms against the green ones and see the change in temperature in the thermometer. Click the reset button. Rub the chemistry textbook against the physics text and note down the temperature difference. When the temperature rise is at its peak, you can see that all the atoms have distributed in all the directions. THERMAL EFFECT Observations Rub your hands together, what do you feel? What do you observe when you rub the books vigorously against each other? Today I learned: THERMAL EFFECT Quiz The force of friction acts in a direction _____ to the direction of motion of the object. Same Opposite Perpendicular Downwards The body will move only when the Force of friction = applied force Force of friction < applied force Force of friction > applied force All of the above The force of friction depends upon the Nature of surface of contact. Material of objects in contact. Both ‘a’ and ‘b’ None of the above. Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play Only if the objects are solid. Only if one of the two objects is liquid. Only if one of the two objects is gaseous. Irrespective of whether the objects are sold, liquid or gaseous. If we apply oil on door hinges, the friction will Increase Decrease Disappear altogether Will remain unchanged. THERMAL EFFECT Reference Fire lighting by friction: Fire can be created through friction by rapidly grinding pieces of solid burnable material (such as wood) against each other or a hard surface. Successfully creating fire by friction involves skill, fitness, knowledge, and acceptable environmental conditions. Some techniques involve crafting a system of interlocking pieces that give the practitioner an improved mechanical advantage; these techniques require more skill and knowledge but less fitness, and work in less ideal conditions. Producing a fire by friction is not comparable to lighting a match, in which case the fire lighting tool has already created a flame for you. With friction fire effort is focused into grinding dust off of soft solid burnable material such that the dust is smoldering. The hand drill is suggested[by whom?] to be the oldest method of fire by friction, characterized by the use of a thin, straightened wooden shaft or reed to be spun with the hands, grinding within a notch against the soft wooden base of a fire board (a wooden board with a carved notch in which to catch heated wood fibers created by friction). This repeated spinning and downward pressure causes black dust to form in the notch of the fireboard, eventually creating a hot, glowing coal. The coal is then carefully placed among dense, fine tinder, which is pressed against it as one blows directly onto the coal until the tinder begins burning and eventually catches into flame. The advantage of the hand drill technique is that it requires no rope, which can be time consuming to produce and wears down rapidly. The bow drill uses the same principle as the hand drill (friction by rotation of wood on wood) but the spindle is shorter, wider (about the size of a human thumb) and driven by a bow, which allows longer, easier strokes and protects the palms. With a well-built bow drill and enough practice, fire can be easily created even in wet conditions. Another simple fire making tool using friction is a fire plough. It consists of a stick cut to a dull point, and a long piece of wood with a groove cut down its length. The point of the first piece is rubbed quickly against the groove of the second piece in a "plowing" motion, to produce hot dust that then becomes a coal. A split is often made down the length of the grooved piece, so that oxygen can flow freely to the coal/ember. Once hot enough, the coal is introduced to the tinder, more oxygen is added by blowing and the result is ignition. A fire-saw is a method by which a piece of wood is sawed through a notch in a second piece or pieces to generate friction. The tinder may be placed between two slats of wood with the third piece or "saw" drawn over them above the tinder so as to catch a coal, but there is more than one configuration. SourcesSource and and Reference: References https://en.wikipedia.org/wiki/Firelighting#Friction .
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