Question

¸ß̨»¬Ñ©Ô˶¯Ô±¾­¹ýÒ»¶Î»¬Ðкó´ÓбÆÂÉϵÄOµãˮƽ·É³ö£¬Ð±ÆÂÓëˮƽÃæµÄ¼Ð½Ç¦È=37¡ã£¬Ô˶¯Ô±Á¬Í¬»¬Ñ©°åµÄ×ÜÖÊÁ¿m=50kg£¬ËûÂäµ½ÁËбÆÂÉϵÄAµã£¬AµãÓëOµãµÄ¾àÀës=12m,Èçͼ14Ëùʾ¡£ºöÂÔбƵÄĦ²ÁºÍ¿ÕÆø×èÁ¦µÄÓ°Ï죬ÖØÁ¦¼ÓËÙ¶Èg=10m/s²¡£

(sin37¡ã=0.60;cos37¡ã=0.80)
(1)Ô˶¯Ô±ÔÚ¿ÕÖзÉÐÐÁ˶೤ʱ¼ä£¿
(2)ÇóÔ˶¯Ô±À뿪OµãʱµÄËٶȴóС¡£
(3)Ô˶¯Ô±Â䵽бÆÂÉÏ˳ÊÆÇüÍÈÒÔ»º³å£¬Ê¹Ëû´¹Ö±ÓÚбƵÄËÙ¶ÈÔÚt=0.50sµÄʱ¼äÄÚ¼õСΪÁ㣬É軺³å½×¶ÎбƶÔÔ˶¯Ô±µÄµ¯Á¦¿ÉÒÔ¿´×÷ºãÁ¦£¬Çó´Ëµ¯Á¦µÄ´óС¡£

Answer 1

£¨1£© 1.2s      £¨2£©8.0m/s                         (3) 880N

(1)ÉèÔ˶¯Ô±ÔÚ¿ÕÖзÉÐÐʱ¼äΪt£¬Ô˶¯Ô±ÔÚÊúÖ±·½Ïò×ö×ÔÓÉÂäÌåÔ˶¯£¬µÃ
ssin37¡ã=gt²£¬
½âµÃ£º                                                         t==1.2s¡£¡­¡­¡­¡­2·Ö
(2)ÉèÔ˶¯Ô±À뿪OµãµÄËÙ¶ÈΪv₀£¬Ô˶¯Ô±ÔÚˮƽ·½Ïò×öÔÈËÙÖ±ÏßÔ˶¯£¬¼´
scos37¡ã=v₀t£¬
½âµÃ£º                                                         v₀==8.0m/s¡£¡­¡­¡­¡­2·Ö
(3)Ô˶¯Ô±ÂäÔÚAµãʱÑØÊúÖ±ÏòϵÄËÙ¶Èv_yµÄ´óСΪ
          v_y=gt="12m/s  " ¡­¡­¡­¡­1·Ö£¬
ÑØˮƽ·½ÏòµÄËÙ¶Èv_xµÄ´óСΪ             v_x=8.0m/s¡£
Òò´Ë£¬Ô˶¯Ô±´¹Ö±ÓÚбÃæÏòϵÄËÙ¶Èv_NΪ
                     v_N=v_ycos37¡ã-v_xsin37¡ã=4.8m/s¡£¡­¡­¡­¡­1·Ö
ÉèÔ˶¯Ô±ÔÚ»º³åµÄ¹ý³ÌÖÐÊܵ½Ð±ÃæµÄµ¯Á¦ÎªN£¬¸ù¾Ý¶¯Á¿¶¨Àí
(N-mgcos37¡ã)t=mv_N£¬¡­¡­¡­¡­1·Ö
½âµÃ£º                                N=mgcos37¡ã+=880N¡£¡­¡­¡­¡­1·Ö