21.6
يتحرك الجسم بتسارع ثابت، ولقد وجدنا تعبيراً للتسارع في البند السابق.
نُشير إلى حركة الجسم من النقطة A إلى النقطة B، ونستخدم تعبير مربع السرعة من قوانين الحركة، ونعبر عن سرعة الجسم في النقطة B.
بدأ الجسم في الحركة من حالة السكون، لذا فإن سرعته الابتدائية تساوي صفرًا.
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نُعوّض المعطيات في التعبير، ونحسب سرعة الجسم في النقطة B:
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ومقدار سرعة البروتون في النقطة B حوالي 400 ألف متر في الثانية.