حلول التدريبات العملية 2 في الكهروستاتيكا

46. 14.4

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mstyle mathsize=¨18px¨»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#931;W«/mi»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mmultiscripts»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»W«/mi»«mprescripts/»«mrow mathcolor=¨#0000FF¨»«mi»§#1582;§#1575;§#1585;§#1580;§#1610;§#1577;«/mi»«mo»§#160;«/mo»«mi»§#1602;§#1608;§#1577;«/mi»«/mrow»«none/»«/mmultiscripts»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»+«/mo»«mmultiscripts»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»W«/mi»«mprescripts/»«mrow mathcolor=¨#0000FF¨»«mi»§#1603;§#1607;§#1585;§#1576;§#1575;§#1574;§#1610;§#1577;«/mi»«mo»§#160;«/mo»«mi»§#1602;§#1608;§#1577;«/mi»«/mrow»«none/»«/mmultiscripts»«/mstyle»«/math»

نُعبّر عن شغل القوة الخارجية ونحسب قيمته:

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mstyle mathsize=¨18px¨»«mmultiscripts»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»W«/mi»«mprescripts/»«mrow mathcolor=¨#0000FF¨»«mi»§#1582;§#1575;§#1585;§#1580;§#1610;§#1577;«/mi»«mo»§#160;«/mo»«mi»§#1602;§#1608;§#1577;«/mi»«/mrow»«none/»«/mmultiscripts»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#931;W«/mi»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«mmultiscripts»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»W«/mi»«mprescripts/»«mrow mathcolor=¨#0000FF¨»«mi»§#1603;§#1607;§#1585;§#1576;§#1575;§#1574;§#1610;§#1577;«/mi»«mo»§#160;«/mo»«mi»§#1602;§#1608;§#1577;«/mi»«/mrow»«none/»«/mmultiscripts»«mspace linebreak=¨newline¨/»«msub»«mspace linebreak=¨newline¨/»«mrow»«mi mathcolor=¨#0000FF¨»§#1582;§#1575;§#1585;§#1580;§#1610;§#1577;«/mi»«mo mathcolor=¨#0000FF¨»§#160;«/mo»«mi mathcolor=¨#0000FF¨»§#1602;§#1608;§#1577;«/mi»«/mrow»«/msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»W«/mi»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»0«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«mrow mathcolor=¨#0000FF¨»«mo stretchy=¨true¨ mathvariant=¨bold¨»(«/mo»«mo mathvariant=¨bold¨»-«/mo»«mn mathvariant=¨bold¨»4«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»86«/mn»«mo mathvariant=¨bold¨»§#183;«/mo»«msup»«mn mathvariant=¨bold¨»10«/mn»«mrow»«mo mathvariant=¨bold¨»-«/mo»«mn mathvariant=¨bold¨»5«/mn»«/mrow»«/msup»«mo stretchy=¨true¨ mathvariant=¨bold¨»)«/mo»«/mrow»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«mmultiscripts»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»W«/mi»«mprescripts/»«mrow mathcolor=¨#0000FF¨»«mi»§#1603;§#1607;§#1585;§#1576;§#1575;§#1574;§#1610;§#1577;«/mi»«mo»§#160;«/mo»«mi»§#1602;§#1608;§#1577;«/mi»«/mrow»«none/»«/mmultiscripts»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»4«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨».«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»86«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#183;«/mo»«msup»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»10«/mn»«mrow mathcolor=¨#0000FF¨»«mo mathvariant=¨bold¨»-«/mo»«mn mathvariant=¨bold¨»5«/mn»«/mrow»«/msup»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»J«/mi»«/mstyle»«/math»

يتحرك الجسم تحت تأثير القوة الكهربائية والقوة الخارجية فقط وبالإضافة إلى ذلك لا يحدث تغيّر في الطاقة الحركية للجسم. 

 ولذلك يمكن استخدام تعبير شغل القوة الخارجية: 

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