Question

19£®2016Äê9ÔÂ1ÈÕ£¬ÊÀ½ç×î´óÔËÊä»ú°²-225Â仧Öйú£¬¸Ã·É»úµÄ×î´óÔØÖØÁ¿¿É´ï300t£¬·É»úÔÚ×î´óÔØÖØ״̬ÏÂÆð·ÉÐèÒª»¬ÅܾàÀë3200m£¬×Ž¾àÀëΪ2400m£¬ÉèÆð·É»¬ÅܺÍ׎¹ý³Ì¶¼ÊÇÔȱäËÙÖ±ÏßÔ˶¯£¬ÒÑÖª·É»úÆð·ÉʱËÙ¶ÈÊÇ׎ʱËٶȵÄ2±¶£¬Ôò¸Ã·É»úÔÚ×î´óÔØÖØ״̬ʱ£¨¡¡¡¡£©

• A£® Æð·É»¬Ðйý³ÌµÄ¼ÓËٶȴóСÊÇ׎»¬Ðйý³Ì¼ÓËٶȴóСµÄ3±¶
• B£® Æð·É»¬Ðйý³ÌµÄ¼ÓËٶȴóСÊÇ׎»¬Ðйý³Ì¼ÓËٶȴóСµÄ2±¶
• C£® Æð·É»¬Ðйý³ÌÓÃʱÊÇ׎»¬Ðйý³ÌÓÃʱµÄ$\frac{2}{3}$
• D£® Æð·É»¬Ðйý³ÌÓÃʱÊÇ׎»¬Ðйý³ÌÓÃʱµÄ1.5±¶

Answer 1

·ÖÎö ¶Ô·É»úÆð·ÉºÍ׎¹ý³Ì·Ö±ð¸ù¾ÝÔȱäËÙÖ±ÏßÔ˶¯µÄËÙ¶ÈλÒƹ«Ê½ÁÐʽ¼´¿ÉÇó³öÁ½¸ö¹ý³ÌµÄ¼ÓËٶȹØϵ£»ÓÉÔȱäËÙÖ±ÏßÔ˶¯µÄƽ¾ùËÙ¶ÈÇóλÒƵĹ«Ê½¼´¿ÉÇó³öʱ¼ä¹Øϵ£»

½â´ð ½â£ºAB¡¢Éè·É»úÆð·ÉµÄËÙ¶ÈΪ${v}_{0}^{\;}$£¬×ŽʱËٶȴóСΪv£¬¸ù¾ÝËÙ¶ÈλÒƹØϵʽÓУº
Æð·Éʱ£º${v}_{0}^{2}=2{a}_{1}^{\;}{x}_{1}^{\;}$¡­¢Ù
׎ʱ£º${v}_{\;}^{2}=2{a}_{2}^{\;}{x}_{2}^{\;}$¡­¢Ú
ÁªÁ¢¢Ù¢ÚµÃ£º$\frac{{a}_{1}^{\;}}{{a}_{2}^{\;}}=\frac{\frac{{v}_{0}^{2}}{2{x}_{1}^{\;}}}{\frac{{v}_{\;}^{2}}{2{x}_{2}^{\;}}}=\frac{{v}_{0}^{2}}{{v}_{\;}^{2}}•\frac{{x}_{2}^{\;}}{{x}_{1}^{\;}}$=$\frac{4}{1}¡Á\frac{2400}{3200}=\frac{3}{1}$£¬¹ÊAÕýÈ·£¬B´íÎó£»
CD¡¢¸ù¾Ýƽ¾ùËÙ¶ÈÇóλÒƵĹ«Ê½$x=\frac{{v}_{0}^{\;}+v}{2}t$
Æð·É»¬Ðйý³Ì${x}_{1}^{\;}=\frac{{v}_{0}^{\;}}{2}{t}_{1}^{\;}$
׎»¬Ðйý³Ì${x}_{2}^{\;}=\frac{v}{2}{t}_{2}^{\;}$
$\frac{{t}_{1}^{\;}}{{t}_{2}^{\;}}=\frac{\frac{2{x}_{1}^{\;}}{{v}_{0}^{\;}}}{\frac{2{x}_{2}^{\;}}{v}}=\frac{{x}_{1}^{\;}}{{x}_{2}^{\;}}•\frac{v}{{v}_{0}^{\;}}=\frac{3200}{2400}¡Á\frac{1}{2}=\frac{2}{3}$£¬¹ÊCÕýÈ·£¬D´íÎó£»
¹ÊÑ¡£ºAC

µãÆÀ ½â¾ö±¾ÌâµÄ¹Ø¼üÕÆÎÕÔȱäËÙÖ±ÏßÔ˶¯µÄÔ˶¯Ñ§¹«Ê½ºÍÍÆÂÛ£¬²¢ÄÜÁé»îÔËÓã¬ÓÐʱÔËÓÃÍÆÂÛÇó½â»áʹÎÊÌâ¸ü¼Ó¼ò½Ý£®