109: Investigate, Recognise and use the expression ^E = mc^0.
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The efect efect that that transe transerr rred ed heat heat energy energy has on on the tempera temperatur ture e o an object depends on three things: o The amount amount o heat energy energy transerr transerred. ed. o The mass o the object. object. o The specic heat heat capacity o the material material rom rom which the object is made. How much the temperat temperature ure rises rises is dependen dependentt upon upon the the natur nature e o the material and this is given by a property property called specic heat capacity ‘c. !pecic !pecic heat heat capacit capacity y is dene dened d as the the amount amount o ener energy gy needed needed to raise raise the temperature o "#g o a particular substance by "$. %ifere %iferent nt materi materials als have have diferent diferent speci specic c heat heat capaciti capacities es becaus because e their their molecular structures are diferent and so their molecules will be afected to diferent degrees by additional heat energy. The e&pr e&press ession ion ' ( mc)*** mc)*** or a certain certain amou amount nt o ener energy gy ‘' ‘' transe transerr rred ed to a material+ the change in temperature ***+ is related to mass o material ‘m and the specic heat capacity+ ‘c. !pec !peci ic c hea heatt capa capaci city ty has has unit units s in in ,#g ,#g-"$ -". ou can can use change change in tempera temperatur ture e ***thet ***theta/+ a/+ in both $elvin $elvin or or 0elsius 0elsius as the intervals are the same on both scales.
110: Explain the concept of internal energ as the random distri!ution of potential and "inetic energ amongst molecules.
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1olecules 1olecules vibrate vibrate or or move move aste asterr when when their their #inetic #inetic energy energy incre increase ases. s. Their potential potential energy energy also changes changes as they move about about aster. aster. 2t is the #ineti #inetic c energy energy that determi determines nes the the temper temperatur ature e o a materia material. l. 2 the the avera average ge #inetic #inetic energy energy o the molec molecules ules o a substance substance increase increases+ s+ then it is at a higher temperature. temperature. This This is 2nte 2nterrnal nal 'ner 'nergy gy. 2nterna 2nternall $inetic $inetic 'nerg 'nergy y on the scale scale o the the partic particles les that that ma# ma#e e up an an object object is separate rom the idea o overall movement o the object. 3 cric#et ball moves due to its #inetic energy but its molecules are vibrating within it and it is this internal #inetic energy that determines its temperature.
111. Explain the concept of a!solute #ero and ho$ the average "inetic energ of molecules is related to the a!solute temperature.
- 2 you ta#e energy away rom a substance+ its temperature becomes lower. 4nce all o this internal energy is ta#en away+ the molecules will not have any internal #inetic energy let. 3t this point+ the temperature o the substance is said to be absolute 5ero. - The gaps in the $elvin $elvin !cale are similar to the 6ahrenheit 6ahrenheit and 0elsius. $elvin scale starts at absolute 5ero at which there is no #inetic energy in molecules. !o the $elvin scale o temperature is sometimes called the absolute temperature. - 3s the units begin rom a denite 5ero and go up in proportion to the amount o energy being added to the molecules o the substance being measured+ it is
clear that as the average #inetic energy o the molecules increases so does the absolute temperature. 11%. Recogni#e and use the expression 1&%mc % = '&%"(.
- The e&pression or the average #inetic energy o the molecules is ( 7 mc 8. ‘c is the speed o the molecule and ‘m is its mass. - The root mean s9uare speed is s9rtc 8/ rom the e&pression above. - The average #inetic energy o any molecule in a gaseous sample is proportional to the absolute temperature o the gas. - This is e&pressed as "8mc8 ( ;8#T where ‘# is the
- 3ssuming a gas is an ideal gas+ we can put together an e9uation relating relating pressure+ volume+ temperature and amount o gas. - p@ ( A#T - where A is the number o molecules o the gas and # is the
