حلول التدريبات العملية حفظ كمية الحركة

1. ايجاد مقدار الدفع J الذي يشغّله الجدار على الجسم أثناء عملية الاصطدام.

حسب قانون الدفع وكمية الحركة: 

   «math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»J«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#8710;«/mo»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»P«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mspace linebreak=¨newline¨/»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»J«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mover mathcolor=¨#0000FF¨»«msub»«mi mathvariant=¨bold¨»P«/mi»«mn mathvariant=¨bold¨»2«/mn»«/msub»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«msub»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»P«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»1«/mn»«/msub»«/math»

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«msub»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»P«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»2«/mn»«/msub»«/math» - كمية الحركة بعد الاصطدام.

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«msub»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»P«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»1«/mn»«/msub»«/math» - كمية الحركة قبل الاصطدام.

نختار اتجاه المحور الموجب إلى اليمين :- 

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«msub»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»v«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»1«/mn»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»5«/mn»«mfrac mathcolor=¨#0000FF¨ bevelled=¨true¨»«mrow»«mo mathvariant=¨bold¨»§#160;«/mo»«mi mathvariant=¨bold¨»m«/mi»«/mrow»«mi mathvariant=¨bold¨»s«/mi»«/mfrac»«mspace linebreak=¨newline¨/»«msub»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»v«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»2«/mn»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»5«/mn»«mfrac mathcolor=¨#0000FF¨ bevelled=¨true¨»«mrow»«mo mathvariant=¨bold¨»§#160;«/mo»«mi mathvariant=¨bold¨»m«/mi»«/mrow»«mi mathvariant=¨bold¨»s«/mi»«/mfrac»«/math»

نُعوّض في معادلة كمية الحركة والدفع:

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»J«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mover mathcolor=¨#0000FF¨»«msub»«mi mathvariant=¨bold¨»P«/mi»«mn mathvariant=¨bold¨»2«/mn»«/msub»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«msub»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»P«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»1«/mn»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»m«/mi»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#183;«/mo»«msub»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»v«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»2«/mn»«/msub»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»m«/mi»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#183;«/mo»«msub»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»v«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»1«/mn»«/msub»«mspace linebreak=¨newline¨/»«mover mathcolor=¨#0000FF¨»«mi mathvariant=¨bold¨»J«/mi»«mo mathvariant=¨bold¨»§#8594;«/mo»«/mover»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»20«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#183;«/mo»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»(«/mo»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»5«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»5«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»)«/mo»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»=«/mo»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»-«/mo»«mn mathvariant=¨bold¨ mathcolor=¨#0000FF¨»200«/mn»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#160;«/mo»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»N«/mi»«mo mathvariant=¨bold¨ mathcolor=¨#0000FF¨»§#183;«/mo»«mi mathvariant=¨bold-italic¨ mathcolor=¨#0000FF¨»S«/mi»«/math»

اتجاه الدفع الذي يشغله الجدار على الجسم هو نحو اليسار.