Question

4£®ÎªÁ˼ල˾»úÊÇ·ñ×ñÊØÏÞËٹ涨£¬½»¹Ü²¿ÃÅÔڸ߶ȹ«Â·ÉÏ°²×°Á˹̶¨²âËÙÒÇ£®ÈçͼËùʾ£¬Æû³µÏò·ÅÖÃÔÚµÀ·ÖмäµÄ²âËÙÒÇÔÈËÙÊ»À´£¬²âËÙÒÇÏòÆû³µ·¢³öÁ½´Î¶Ì´ÙµÄ³¬Éù²¨Ðźţ®µÚÒ»´Î·¢³öÐźŵ½²âËÙÒǽÓÊÕµ½¾­Æû³µ·´Éä»ØÀ´µÄÐźÅÓÃʱ0.4s£¬µÚ¶þ´Î·¢³öÐźŵ½²âËÙÒǽÓÊÕµ½¾­Æû³µ·´Éä»ØÀ´µÄÐźÅÓÃʱ0.2s£¬Èô·¢³öÁ½´ÎÐźŵÄʱ¼ä¼ä¸ôÊÇ1.1s£¬³¬Éù²¨µÄËÙ¶ÈÊÇ340m/s£¬Çó£º
£¨1£©Æû³µ½ÓÊÕµ½µÚÒ»´ÎÐźÅʱ£¬¾à²âËÙÒǵľàÀ룻
£¨2£©Æû³µ´Ó½ÓÊÕµ½µÚÒ»´ÎÐźŵ½½ÓÊܵ½µÚ¶þ´ÎÐźŹý³ÌÖУ¬ÐÐÊ»µÄ¾àÀ룻
£¨3£©Èô´Ë·¶ÎÏÞËÙΪ120km/h£¬ÊÔ¼ÆËã˵Ã÷Æû³µÔÚ´Ë·¶ÎÊÇ·ñ³¬ËÙ£¿

Answer 1

·ÖÎö ÇóÆû³µµÄËٶȱØÐëÖªµÀÐÐÊ»µÄ¾àÀëºÍÏàÓ¦µÄʱ¼ä£º
¢Ù²âËÙÒǵÚÒ»´Î·¢³ö³¬Éù²¨Ê±£¬¾­¹ýÁË0.2sµ½´ïÁËÆû³µ´¦£¬¶øÐźŴÓÆû³µ´¦·µ»Ø²âËÙÒÇ£¬Ò²ÐÐÊ»ÁË0.2sµÄʱ¼ä£»
¢ÚÔÚµÚ¶þ´Î·¢³öµÄÐźţ¬ÔÚÓëÆû³µÏàÓö·µ»Øµ½²âËÙÒÇʱ£¬³¬Éù²¨ÐÐÊ»ÁË0.1s£»
¢ÛÕâÁ½´ÎÆû³µÓë²âËÙÒǵľàÀë²î¾ÍÊÇÆû³µÐÐÊ»µÄ¾àÀ룬ÔÙÕÒ³öÐÐÊ»Õâ¶Îʱ¼äËùÓõÄʱ¼ä£¨Æû³µÔ˶¯µÄʱ¼äΪ´ÓµÚÒ»´ÎÓ볬Éù²¨ÏàÓö¿ªÊ¼£¬µ½µÚ¶þ´ÎÓ볬Éù²¨ÏàÓö½áÊø£¬
Çó³öÕâ¸öʱ¼ä£¬¾ÍÊÇÆû³µÔ˶¯µÄʱ¼ä£©£¬ÀûÓÃËٶȹ«Ê½¼´¿ÉµÃ½â£®

½â´ð ½â£º£¨1£©²âËÙÒǵÚÒ»´Î·¢³ö³¬Éù²¨µ½´ïÆû³µ´¦ËùÓõÄʱ¼ät₁=$\frac{0.4s}{2}$=0.2s£¬
ÓÉv=$\frac{s}{t}$µÃ£¬Æû³µ½ÓÊÕµ½µÚÒ»´ÎÐźÅʱ£¬¾à²âËÙÒǵľàÀ룺
s₁=v_Éùt₁=340m/s¡Á0.2s=68m£®
£¨2£©²âËÙÒǵڶþ´Î·¢³ö³¬Éù²¨µ½´ïÆû³µ´¦ËùÓõÄʱ¼ät₂=$\frac{0.2s}{2}$=0.1s£¬
Æû³µ½ÓÊÕµ½µÚ¶þ´ÎÐźÅʱ£¬¾à²âËÙÒǵľàÀ룺
s₂=v_Éùt₂=340m/s¡Á0.1s=34m£»
Æû³µ´Ó½ÓÊÕµ½µÚÒ»´ÎÐźŵ½½ÓÊܵ½µÚ¶þ´ÎÐźŹý³ÌÖУ¬ÐÐÊ»µÄ¾àÀ룺
s=s₂-s₁=68m-34m=34m£®
£¨3£©Æû³µ´Ó½ÓÊÕµ½µÚÒ»´ÎÐźŵ½½ÓÊܵ½µÚ¶þ´ÎÐźŹý³ÌÖУ¬ÐÐÊ»µÄʱ¼ä£º
t=¡÷t-t₁+t₂=1.1s-0.2s+0.1s=1s£¬
ËùÒÔÆû³µµÄ³µËÙΪ£º
v=$\frac{s}{t}$=$\frac{34m}{1s}$=34m/s=122.4km/h£®
ÒòΪv=122.4km/h£¾120km/h£¬ËùÒÔÆû³µÔÚ´Ë·¶Î³¬ËÙ£®
´ð£º£¨1£©Æû³µ½ÓÊÕµ½µÚÒ»´ÎÐźÅʱ£¬¾à²âËÙÒǵľàÀëΪ68m£»
£¨2£©Æû³µ´Ó½ÓÊÕµ½µÚÒ»´ÎÐźŵ½½ÓÊܵ½µÚ¶þ´ÎÐźŹý³ÌÖУ¬ÐÐÊ»µÄ¾àÀëΪ34m£»
£¨3£©Æû³µÔÚ´Ë·¶Î³¬ËÙ£®

µãÆÀ ±¾Ì⿼²éÁËѧÉú¶ÔËٶȹ«Ê½µÄÓ¦Óã¬ÈçºÎÈ·¶¨Æû³µÔ˶¯µÄʱ¼ä£¬ÊÇ´ËÌâµÄÄѵ㣮Á½´ÎÐźŵÄʱ¼ä¼ä¸ôËäÈ»ÊÇ1.1Ã룬µ«Æû³µÔÚ½ÓÊÕµ½Á½´ÎÐźÅʱÆäÆäͨ¹ýµÄ·³ÌËù¶ÔÓ¦µÄʱ¼ä²»ÊÇ1.1Ã룮
Òª´ÓÆðµÚÒ»´Î½ÓÊÕµ½³¬Éù²¨µÄÐźſªÊ¼¼Æʱ£¬µ½µÚ¶þ´Î½ÓÊÕµ½³¬Éù²¨µÄÐźŽáÊø£¬ÓÉ´ËÀ´È·¶¨ÆäÔ˶¯Ê±¼ä£®Í¨¹ýµÄ·³ÌÓëͨ¹ýÕâ¶Î·³ÌËùÓõÄʱ¼ä¶ÔÓ¦ÉÏÊǽâ¾ö´ËÌâ¹Ø¼ü£®