7.3
נערוך תרשים כוחות לכוחות הפועלים על q3 ונסמן את המרחק בין q1 ל q3 ב r1,3 ואת המרחק בין q2 ל q3 ב r2,3.
שקול הכוחות הפועלים במצב זה על q3 שווה לאפס. נכתוב את משוואת התנועה:
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mstyle mathsize=¨22px¨»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»§#931;«/mi»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»F«/mi»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»0«/mn»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«msub»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»F«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«msub»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»F«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»2«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«mfrac mathcolor=¨#0000FF¨»«mrow»«mi mathvariant=¨bold¨»K«/mi»«mo mathvariant=¨bold¨»§#183;«/mo»«msub»«mi mathvariant=¨bold¨»q«/mi»«mn mathvariant=¨bold¨»1«/mn»«/msub»«mo mathvariant=¨bold¨»§#183;«/mo»«msub»«mi mathvariant=¨bold¨»q«/mi»«mn mathvariant=¨bold¨»3«/mn»«/msub»«/mrow»«msup»«msub»«mi mathvariant=¨bold¨»r«/mi»«mrow»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨»2«/mn»«/msup»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mfrac mathcolor=¨#0000FF¨»«mrow»«mi mathvariant=¨bold¨»K«/mi»«mo mathvariant=¨bold¨»§#183;«/mo»«msub»«mi mathvariant=¨bold¨»q«/mi»«mn mathvariant=¨bold¨»2«/mn»«/msub»«mo mathvariant=¨bold¨»§#183;«/mo»«msub»«mi mathvariant=¨bold¨»q«/mi»«mn mathvariant=¨bold¨»3«/mn»«/msub»«/mrow»«msup»«msub»«mi mathvariant=¨bold¨»r«/mi»«mrow»«mn mathvariant=¨bold¨»2«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨»2«/mn»«/msup»«/mfrac»«/mstyle»«/math»
נבצע פעולות צמצום ונציב את ערכי המטענים:
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mfrac mathcolor=¨#0000FF¨»«mrow»«menclose notation=¨updiagonalstrike¨»«mi mathvariant=¨bold¨ mathsize=¨22px¨»K«/mi»«/menclose»«mo mathvariant=¨bold¨ mathsize=¨22px¨»§#183;«/mo»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»q«/mi»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«/msub»«mo mathvariant=¨bold¨ mathsize=¨22px¨»§#183;«/mo»«menclose notation=¨downdiagonalstrike¨»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»q«/mi»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/msub»«/menclose»«/mrow»«msup»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msup»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨ mathsize=¨22px¨»=«/mo»«mfrac mathcolor=¨#0000FF¨»«mrow»«menclose notation=¨updiagonalstrike¨»«mi mathvariant=¨bold¨ mathsize=¨22px¨»K«/mi»«/menclose»«mo mathvariant=¨bold¨ mathsize=¨22px¨»§#183;«/mo»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»q«/mi»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msub»«mo mathvariant=¨bold¨ mathsize=¨22px¨»§#183;«/mo»«menclose notation=¨downdiagonalstrike¨»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»q«/mi»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/msub»«/menclose»«/mrow»«msup»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msup»«/mfrac»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«mfrac mathcolor=¨#0000FF¨»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»q«/mi»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«/msub»«msup»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msup»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨ mathsize=¨22px¨»=«/mo»«mfrac mathcolor=¨#0000FF¨»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»q«/mi»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msub»«msup»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msup»«/mfrac»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«mfrac mathcolor=¨#0000FF¨»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»5«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»§#183;«/mo»«msup»«mn mathvariant=¨bold¨ mathsize=¨22px¨»10«/mn»«mrow»«mo mathvariant=¨bold¨ mathsize=¨22px¨»-«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»9«/mn»«/mrow»«/msup»«/mrow»«msup»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msup»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨ mathsize=¨22px¨»=«/mo»«mfrac mathcolor=¨#0000FF¨»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»7«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»§#183;«/mo»«msup»«mn mathvariant=¨bold¨ mathsize=¨22px¨»10«/mn»«mrow»«mo mathvariant=¨bold¨ mathsize=¨22px¨»-«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»9«/mn»«/mrow»«/msup»«/mrow»«msup»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msup»«/mfrac»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«mfrac mathcolor=¨#0000FF¨»«msup»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msup»«msup»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/msup»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨ mathsize=¨22px¨»=«/mo»«mfrac mathcolor=¨#0000FF¨»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»7«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»§#183;«/mo»«msup»«mn mathvariant=¨bold¨ mathsize=¨22px¨»10«/mn»«mrow»«mo mathvariant=¨bold¨ mathsize=¨22px¨»-«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»9«/mn»«/mrow»«/msup»«/mrow»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»5«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»§#183;«/mo»«msup»«mn mathvariant=¨bold¨ mathsize=¨22px¨»10«/mn»«mrow»«mo mathvariant=¨bold¨ mathsize=¨22px¨»-«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»9«/mn»«/mrow»«/msup»«/mrow»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨ mathsize=¨22px¨»=«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨ mathsize=¨22px¨»1«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨ mathsize=¨22px¨».«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨ mathsize=¨22px¨»4«/mn»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«menclose mathcolor=¨#0000FF¨ notation=¨box¨»«mfrac»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«/mfrac»«mo mathvariant=¨bold¨ mathsize=¨22px¨»=«/mo»«msqrt»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨».«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»4«/mn»«/msqrt»«/menclose»«/math»
סכום המרחקים r2,3 ו- r1,3 שווה למרחק d, שערכו 2 מטרים.
נכתוב בהתאם משוואה נוספת עם אותם שני נעלמים: r2,3 ו- r1,3 .
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«menclose mathcolor=¨#0000FF¨ notation=¨box¨»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»1«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathsize=¨22px¨»+«/mo»«msub»«mi mathvariant=¨bold¨ mathsize=¨22px¨»r«/mi»«mrow»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«mo mathvariant=¨bold¨ mathsize=¨22px¨»,«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathsize=¨22px¨»=«/mo»«mn mathvariant=¨bold¨ mathsize=¨22px¨»2«/mn»«/menclose»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«/math»
נבטא משתי המשוואות את המרחק הדרוש r1,3:
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mstyle mathsize=¨20px¨»«menclose mathcolor=¨#0000FF¨ notation=¨box¨»«msub»«mi mathvariant=¨bold¨»r«/mi»«mrow»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨»+«/mo»«msub»«mi mathvariant=¨bold¨»r«/mi»«mrow»«mn mathvariant=¨bold¨»2«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨»=«/mo»«mn mathvariant=¨bold¨»2«/mn»«/menclose»«mo»§#160;«/mo»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#8658;«/mo»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»r«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»2«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»2«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»r«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«/mstyle»«/math»
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mstyle mathsize=¨22px¨»«mspace linebreak=¨newline¨/»«menclose mathcolor=¨#0000FF¨ notation=¨box¨»«mfrac»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#FF0000¨»r«/mi»«mrow mathcolor=¨#FF0000¨»«mn mathvariant=¨bold¨»2«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«msub»«mi mathvariant=¨bold¨»r«/mi»«mrow»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«/mfrac»«mo mathvariant=¨bold¨»=«/mo»«msqrt»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»4«/mn»«/msqrt»«/menclose»«mo»§#160;«/mo»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#8658;«/mo»«mfrac mathcolor=¨#0000FF¨»«mrow»«mn mathvariant=¨bold¨ mathcolor=¨#FF0000¨»2«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#FF0000¨»-«/mo»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#FF0000¨»r«/mi»«mrow mathcolor=¨#FF0000¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«/mrow»«msub»«mi mathvariant=¨bold¨»r«/mi»«mrow»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«msqrt mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»4«/mn»«/msqrt»«/mstyle»«/math»
נבטא את המרחק r1,3:
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mstyle mathsize=¨22px¨»«mfrac mathcolor=¨#0000FF¨»«mrow»«mn mathvariant=¨bold¨»2«/mn»«mo mathvariant=¨bold¨»-«/mo»«msub»«mi mathvariant=¨bold¨»r«/mi»«mrow»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«/mrow»«msub»«mi mathvariant=¨bold¨»r«/mi»«mrow»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«msqrt mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»4«/mn»«/msqrt»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»2«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»r«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»r«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#183;«/mo»«msqrt mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»4«/mn»«/msqrt»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»2«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»r«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»+«/mo»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»r«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#183;«/mo»«msqrt mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»4«/mn»«/msqrt»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»2«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»r«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mrow mathcolor=¨#0000FF¨»«mo mathvariant=¨bold¨ stretchy=¨true¨»(«/mo»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»+«/mo»«msqrt»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»4«/mn»«/msqrt»«mo mathvariant=¨bold¨ stretchy=¨true¨»)«/mo»«/mrow»«mspace linebreak=¨newline¨/»«mspace linebreak=¨newline¨/»«msub»«mi mathvariant=¨bold¨ mathcolor=¨#0000FF¨»r«/mi»«mrow mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»,«/mo»«mn mathvariant=¨bold¨»3«/mn»«/mrow»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mfrac mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»2«/mn»«mrow»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨»+«/mo»«msqrt»«mn mathvariant=¨bold¨»1«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»4«/mn»«/msqrt»«/mrow»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mfrac mathcolor=¨#0000FF¨»«mn mathvariant=¨bold¨»2«/mn»«mrow»«mn mathvariant=¨bold¨»2«/mn»«mo mathvariant=¨bold¨».«/mo»«mn mathvariant=¨bold¨»18«/mn»«/mrow»«/mfrac»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»0«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨».«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»91«/mn»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»m«/mi»«/mstyle»«/math»
לסיכום: כאשר מטען q2 שווה 7nC ומטען q1 שווה 5nC הנקודה בה יש למקם את המטען q3 ושקול הכוחות עליו יהיה אפס נמצא 91 ס"מ משמאל ל q1.