Question

20£®Ò»µ«·¢Éú»ðÔÖ£¬¸ß§¾ÓÃñÈçºÎÌÓÉúÒ»Ö±À§ÈÅÎÒÃÇ£¬×î½üÓÐÒ»ÖÖÐÂÐÍÌÓÉú»¬ÌÝÌṩÁËÆľߴ´ÒâµÄ½â¾ö·½Ê½£¬ÕâÖÖ×°ÖÃÀàËÆ¡°»¬»¬ÌÝ¡±£¬½ô¼±Çé¿öʱ·ÅÏ£¬ÌÓÉúÕßÒÐÌÉÔÚ»¬ÌÝÄÚ£¬¼´¿É˳ÊÆ»¬µ½µ×Â¥£®¾­·¢Ã÷Õß²âÊÔ£¬12s¼´¿É´Ó5Â¥»¬µ½1Â¥£¬¼ÙÉ軬ÌÝƶÈΪ30¡ã£¬ºöÂÔת½Ç´¦µÄÄÜÁ¿ËðʧºÍ¿ÕÆø×èÁ¦£¬¼ÙÉèij¸ßÂ¥ÓÐ25²ã£¬Ã¿²ãÂ¥¸ßÔ¼3m£¬ÊÔ¹ÀË㣺
£¨1£©Ï»¬¹ý³ÌÖÐÈ˵ļÓËٶȴóС£»
£¨2£©´Ó¶¥²ã»¬µ½Ò»Â¥ËùÐèµÄʱ¼ä£»
£¨3£©ÈË»¬ÌÝÖ®¼äµÄ¶¯Ä¦²ÁÒòÊý£®

Answer 1

·ÖÎö £¨1£©¸ù¾ÝÔȱäËÙÖ±ÏßÔ˶¯µÄλÒÆʱ¼ä¹«Ê½µÃ³öÏ»¬µÄ¼ÓËٶȴóС£®
£¨2£©¸ù¾ÝλÒÆʱ¼ä¹«Ê½Çó³ö´Ó¶¥²ã»¬µ½Ò»Â¥ËùÐèµÄʱ¼ä£®
£¨3£©¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉÇó³öÈËÓ뻬ÌÝÖ®¼äµÄ¶¯Ä¦²ÁÒòÊý£®

½â´ð ½â£º£¨1£©´Ó5Â¥µ½1Â¥µÄ¸ß¶Èh=4¡Á3m=12m£¬
¸ù¾Ýs=$\frac{1}{2}a{t}^{2}$µÃ£¬a=$\frac{2s}{{t}^{2}}=\frac{2¡Á12¡Á2}{1{2}^{2}}=\frac{1}{3}m/{s}^{2}$£®
£¨2£©¶¥²ãµ½1Â¥µÄ¸ß¶ÈH=25¡Á3m=75m£¬
¸ù¾Ý$\frac{H}{sin30¡ã}=\frac{1}{2}at{¡ä}^{2}$µÃ£¬´Ó¶¥²ã»¬µ½Ò»Â¥µÄʱ¼ät¡ä=$\sqrt{\frac{2¡Á75¡Á2}{\frac{1}{3}}}s$=30s£®
£¨3£©¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨Âɵã¬mgsin¦È-¦Ìmgcos¦È=ma£¬
½âµÃ$¦Ì=\frac{gsin¦È-a}{gcos¦È}$=$\frac{5-\frac{1}{3}}{5\sqrt{3}}$=$\frac{14\sqrt{3}}{45}$£®
´ð£º£¨1£©Ï»¬¹ý³ÌÖÐÈ˵ļÓËٶȴóСΪ$\frac{1}{3}m/{s}^{2}$£»
£¨2£©´Ó¶¥²ã»¬µ½Ò»Â¥ËùÐèµÄʱ¼äΪ30s£»
£¨3£©ÈË»¬ÌÝÖ®¼äµÄ¶¯Ä¦²ÁÒòÊýΪ$\frac{14\sqrt{3}}{45}$£®

µãÆÀ ±¾Ì⿼²éÁËÅ£¶ÙµÚ¶þ¶¨ÂɺÍÔ˶¯Ñ§¹«Ê½µÄ×ÛºÏÔËÓã¬ÖªµÀ¼ÓËÙ¶ÈÊÇÁªÏµÁ¦Ñ§ºÍÔ˶¯Ñ§µÄÇÅÁº£¬ÄѶȲ»´ó£®