Question

2£®ÖÊÁ¿ÎªmµÄÆû³µÔÚƽֱ·ÃæÉÏÆô¶¯£¬Æô¶¯¹ý³ÌµÄËÙ¶ÈͼÏóÈçͼËùʾ£¬´Ót₁ʱ¿ÌÆðÆû³µµÄ¹¦Âʱ£³Ö²»±ä£¬Õû¸öÔ˶¯¹ý³ÌÖÐÆû³µËùÊÜ×èÁ¦ºãΪF_f£¬Ôò£¨¡¡¡¡£©

• A£® t₁¡«t₂ʱ¼äÄÚ£¬Æû³µµÄƽ¾ùËٶȵÈÓÚ$\frac{{v}_{1}+{v}_{2}}{2}$
• B£® 0¡«t₁ʱ¼äÄÚ£¬Æû³µµÄÇ£ÒýÁ¦µÈÓÚm$\frac{{v}_{1}}{{t}_{1}}$
• C£® t₁¡«t₂ʱ¼äÄÚ£¬Æû³µµÄ¹¦ÂʵÈÓÚ£¨m$\frac{{v}_{1}}{{t}_{1}}$+F_f£©v₁
• D£® Æû³µÔ˶¯µÄ¹ý³ÌÖÐ×î´óËÙ¶Èv₂=$\frac{m{v}_{1}^{2}}{{F}_{f}{t}_{1}}$

Answer 1

·ÖÎö ¸ù¾ÝËÙ¶Èʱ¼äͼÏßÇó³öÔȼÓËÙÔ˶¯µÄ¼ÓËٶȣ¬¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉÇó³öÇ£ÒýÁ¦£¬½áºÏÔȼÓËÙÔ˶¯µÄÄ©Ëٶȣ¬¸ù¾ÝP=FvÇó³öÆû³µµÄ¶î¶¨¹¦ÂÊ£®
µ±Æû³µËÙ¶È×î´óʱ£¬Ç£ÒýÁ¦µÈÓÚ×èÁ¦£¬½áºÏP=fvÇó³ö×î´óËٶȣ®

½â´ð ½â£ºA¡¢t₁¡«t₂ʱ¼äÄÚ£¬Æû³µ×ö±ä¼ÓËÙÔ˶¯£¬Æ½¾ùËٶȲ»µÈÓÚ$\frac{{v}_{1}+{v}_{2}}{2}$£¬¹ÊA´íÎó£®
B¡¢0¡«t₁ʱ¼äÄÚ£¬Æû³µµÄ¼ÓËÙ¶Èa=$\frac{{v}_{1}}{{t}_{1}}$£¬¸ù¾ÝÅ£¶ÙµÚ¶þ¶¨ÂÉÖª£¬Æû³µËùÊܵĺÏÁ¦${F}_{ºÏ}=ma=m\frac{{v}_{1}}{{t}_{1}}$£¬ÔòÇ£ÒýÁ¦´óÓÚ$m\frac{{v}_{1}}{{t}_{1}}$£¬¹ÊB´íÎó£®
C¡¢Æû³µÔȼÓËÙÔ˶¯£¬ÓÐF-F_f=ma£¬½âµÃF=${F}_{f}+m\frac{{v}_{1}}{{t}_{1}}$£¬ÔòÆû³µµÄ¹¦ÂÊP=Fv₁=$£¨m\frac{{v}_{1}}{{t}_{1}}+{F}_{f}£©{v}_{1}$£¬¹ÊCÕýÈ·£®
D¡¢Æû³µµÄ¶î¶¨¹¦ÂÊP=$£¨m\frac{{v}_{1}}{{t}_{1}}+{F}_{f}£©{v}_{1}$£¬µ±ËÙ¶È×î´óʱ£¬Ç£ÒýÁ¦µÈÓÚ×èÁ¦£¬Ôò×î´óËÙ¶È${v}_{2}=\frac{P}{{F}_{f}}=\frac{£¨m\frac{{v}_{1}}{{t}_{1}}+{F}_{f}£©{v}_{1}}{{F}_{f}}$£¬¹ÊD´íÎó£®
¹ÊÑ¡£ºC£®

µãÆÀ ½â¾ö±¾ÌâµÄ¹Ø¼üÀíÇåºã¶¨¹¦ÂÊÆô¶¯ºÍºã¶¨¼ÓËٶȵÄÆô¶¯¹ý³ÌÖУ¬¶ÔÓں㶨¼ÓËÙ¶ÈÆô¶¯£¬µ±ÔȼÓËÙÔ˶¯Ëٶȴﵽ×î´óʱ£¬¹¦ÂÊ´ïµ½¶î¶¨¹¦ÂÊ£¬µ±¼ÓËÙ¶ÈΪÁãʱ£¬ËÙ¶È×î´ó£®