Laws of Thermodynamics & Wave Motion

• Fist Law of Thermodynamics : heat added to a system is equal to increase in internal energy plus the external work done
• second law of thermodynamics : the entropy of an isolated system not in equilibrium will tend to increase over rime, approaching a maximum value at equilibrium
• entropy : describe the natural dispersing or degrading of energy, measure : amount of disorder
• third law of thermodynamics : as temperature approaches absolute zero, the entropy of a system approaches a constant minimum
• zeroth law of thermodynamics : if 2 thermodynamics system are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other
• thermal equilibrium : 2 substances have the same temperature & there is no other exchange of heat energy between them
• Vibration is the periodic wiggle in time
• wave is the periodic wiggle in both space and time
• sound is a mechanical wave
• if there is no medium to vibrate, then no sound is possible
• sound waves cannot travel in a vacuum
• light can travel in vacuum
• amount of energy carried by a wave directly depends on its amplitude
• energy and frequency are directly related to each other
• transverse wave is the particles in the medium wave back & forth at right angles to the direction that the wave travel
• crest is the highest point
• trough is the lowest point in the wave
• longitudinal waves is also called compressional waves, motion of the matter in the medium moves back & forth along the same direction that the wave travels
• rarefactions are the region that are spread apart of less dense
• surface waves exhibit both characteristics of transverse and longitudinal waves, only the particles at the surface of the medium that undergo the circular motion
• wavelength is the horizontal distance between 2 successive similar points on a wave
• amplitude is the measure of how far the particles are being moved or disturbed from their resting position
• frequency is the no. of complete cycle of a wave passing a point per unit time or oscillation per second
• period is the time it takes to complete a cycle, expressed in second
• interference is the process of 2 or more waves overlapping and combining to form a new wave
• wavelength and frequency are inversely proportional to each other
• constructive interference : the waves add together, superposition principle

  • amplitude of the new wave that form is equal to the sum of the amplitudes of the original wave
• destructive interference : when the crest of 1 transverse wave meet throughs of another transverse wave , the compression of a wave overlaps with the rarefactions of another longitudinal wave