Question

3£®ÈçͼËùʾ£¬Èý½ÇÐδ«ËÍ´øÒÔ1m/sµÄËÙ¶ÈÄæʱÕëÔÈËÙת¶¯£¬Á½±ßµÄ´«ËÍ´ø³¤¾ùΪ2m£¬ÇÒÓëˮƽ·½ÏòµÄ¼Ð½Ç¾ùΪ30¡ã£®ÏÖÓÐÁ½Ð¡Îï¿éM¡¢N´Ó´«ËÍ´ø¶¥¶Ë¾ùÒÔ1m/sµÄ³õËÙ¶ÈÑØ´«ËÍ´øÏ»¬£¬Îï¿éÓë´«ËÍ´ø¼äµÄ¶¯Ä¦²ÁÒòÊý¾ùΪ$\frac{\sqrt{3}}{3}$£¬ÏÂÁÐ˵·¨ÕýÈ·µÄÊÇ£¨¡¡¡¡£©

• A£® Îï¿éMµ½´ï´«ËÍ´øµ×¶ËµÄËٶȴóСΪ2m/s
• B£® Îï¿éNµ½´ï´«ËÍ´øµ×¶ËµÄËÙ¶ÈΪ0
• C£® Îï¿éM¡¢Nͬʱµ½´ï´«ËÍ´øµ×¶Ë
• D£® Îï¿éM¡¢NÔÚ´«Ñ¡´øÉϵĻ®ºÛ³¤¶ÈÏàͬ

Answer 1

·ÖÎö ´«ËÍ´øÄæʱÕëת¶¯£¬MµÄ³õËÙ¶ÈÓë´«ËÍ´øÏàµÈ£¬Í¨¹ý¶ÔMÊÜÁ¦·ÖÎöÈ·¶¨MµÄÔ˶¯Çé¿ö£»NµÄ³õËٶȷ½ÏòÓë´«ËÍ´øµÄÔ˶¯·½ÏòÏà·´£¬ËùÒÔNÏà¶Ô´«ËÍ´øÏòÏÂÔ˶¯£¬Êܵ½ÑØбÃæÏòÉϵÄĦ²ÁÁ¦£¬¸ù¾ÝÊÜÁ¦·ÖÎöÈ·¶¨NµÄÔ˶¯Çé¿ö£¬¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂɺÍÔ˶¯Ñ§¹«Ê½·ÖÎö¸÷Ñ¡Ï

½â´ð ½â£ºA¡¢¶ÔM£º³õËÙ¶ÈÑØбÃæÏòÏÂÓë´«ËÍ´øËÙ¶ÈÏàͬ£¬ÓÖÒòΪmgsin30¡ã=¦Ìmgcos30¡ã£¬ËùÒÔMÓë´«ËÍ´øÏà¶Ô¾²Ö¹Ò»ÆðÑØ´«ËÍ´øÏòÏÂ×öÔÈËÙÔ˶¯£¬µ½´ï´«ËÍ´øµ×¶ËʱËÙ¶ÈΪ1m/s£¬¹ÊA´íÎó£®
B¡¢¶ÔN£º³õËٶȷ½ÏòÓë´«ËÍ´øÔ˶¯·½ÏòÏà·´£¬NÏà¶Ô´«ËÍ´øÑØбÃæÏòÏÂÔ˶¯£¬Ä¦²ÁÁ¦ÑØ´«ËÍ´øÏòÉÏ£¬¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉmgsin30¡ã-¦Ìmgcos30¡ã=ma£¬½âµÃa=0£¬ËùÒÔNÒ²ÑØбÃæÏòÏÂ×öÔÈËÙÔ˶¯£¬µ½´ï´«ËÍ´øµ×¶ËʱµÄËÙ¶ÈΪ1m/s£¬¹ÊB´íÎó£®
C¡¢MºÍNÑØбÃæÔÈËÙÔ˶¯µÄλÒƺÍËٶȾùÏàͬ£¬¹Êʱ¼äÏàµÈ£¬¹Êͬʱµ½´ï´«ËÍ´øµ×¶Ë£®¹ÊCÕýÈ·£®
D¡¢MÓë´«ËÍ´øÏà¶Ô¾²Ö¹£¬ÔÚ´«ËÍ´øÉÏ»®ºÛΪ0£»NÔÚ´«ËÍ´øÉÏÔ˶¯Ê±¼ä$t=\frac{s}{v}=\frac{2}{1}=2s$£¬´«ËÍ´øλÒÆ${x}_{1}^{\;}={v}_{´«}^{\;}t=2m$£¬${x}_{N}^{\;}=2m$£¬¡÷x=4m£¬NÔÚ´«ËÍ´øÉÏ»®ºÛΪ4m£¬¹ÊD´íÎó£®
¹ÊÑ¡£ºC

µãÆÀ ´¦ÀíÇãб·ÅÖÃÔËÐеĴ«ËÍ´øÎÊÌ⣬ÏȶÔÎïÌåÊÜÁ¦·ÖÎö£¬ÅжÏĦ²ÁÁ¦·½ÏòÊǽâ¾öÎÊÌâµÄ¹Ø¼ü£®