ÌâÄ¿ÄÚÈÝ
10£®Ä³Ãñ¾¯¼ÝʻСÆû³µÔÚһƽֱ¹«Â·ÉÏ×öÆû³µ°²È«¾àÀë²âÊÔʵÑ飬ËûÔÈËÙÐÐʻʱ£¬Æû³µÉÏ¡°ËÙ¶È±í¡±ÈçͼËùʾ£®ÒÑ֪ɲ³µºóÆû³µ×öÔȼõËÙÔ˶¯µÄ×î´ó¼ÓËٶȴóС¦Á=5m/s2£¬Èç¹ûijʱ¿Ì½Óµ½Ö¸Ê¾ÐèҪͣ³µ£¬¸ÃÃñ¾¯µÄ·´Ó¦Ê±¼ät1=0.45s£¬Íê³Éɲ³µ¶¯×÷ËùÐèʱ¼ät2=0.05s£¨ÔÚ´Ëʱ¼äÄÚÆû³µÒÀÈ»°´ÔËÙ¶ÈÇ°½ø£©£¬Ç󣺣¨1£©¸ù¾Ý¡°ËÙ¶È±í¡±£¬¶Á³öСÆû³µµ±Ê±µÄËÙ¶Èv0£®
£¨2£©´Ó½Óµ½Ö¸Ê¾µ½Æû³µÍ£Ï£¬ËùÓÃʱ¼ät£®
£¨3£©´Ó½Óµ½Ö¸Ê¾µ½Ð¡Æû³µÍ£Ï£¬Æû³µÔ˶¯µÄ¾àÀ룮
·ÖÎö ¸ù¾ÝËٶȼƵÄʾÊý¶Á³öСÆû³µµ±Ê±µÄËٶȣ®
¸ù¾ÝËÙ¶Èʱ¼ä¹«Ê½Çó³öÔȼõËÙÖ±ÏßÔ˶¯µÄʱ¼ä£¬´Ó¶øµÃ³ö´Ó½Óµ½Ö¸Ê¾µ½Æû³µÍ£ÏÂËùÐèµÄʱ¼ä£®
¸ù¾Ý·´Ó¦Ê±¼äÄÚµÄλÒÆÒÔ¼°ÔȼõËÙÖ±ÏßÔ˶¯µÄλÒÆ£¬Çó³öÆû³µÔ˶¯µÄ¾àÀ룮
½â´ð ½â£º£¨1£©ÓÉͼ¿ÉÖª£¬ËٶȼƵĶÁÊýΪ72km/h=20m/s£®
£¨2£©Æû³µÔȼõËÙÖ±ÏßÔ˶¯µÄʱ¼äΪ£º${t}_{3}=\frac{{v}_{0}}{a}=\frac{20}{5}s=4s$£¬
Ôò´Ó½Óµ½Ö¸Ê¾µ½Æû³µÍ£ÏÂËùÐèµÄʱ¼äΪ£ºt=t1+t2+t3=0.45+0.05+4s=4.5s£®
£¨3£©´Ó½Óµ½Ö¸Ê¾µ½Ð¡Æû³µÍ£Ï£¬Æû³µÔ˶¯µÄ¾àÀëΪ£ºx=${v}_{0}£¨{t}_{1}+{t}_{2}£©+\frac{{{v}_{0}}^{2}}{2a}$=$20¡Á£¨0.45+0.05£©+\frac{400}{2¡Á5}$m=50m£®
´ð£º£¨1£©Ð¡Æû³µµ±Ê±µÄËÙ¶ÈΪ20m/s£»
£¨2£©´Ó½Óµ½Ö¸Ê¾µ½Æû³µÍ£Ï£¬ËùÓÃʱ¼äΪ4.5s£»
£¨3£©´Ó½Óµ½Ö¸Ê¾µ½Ð¡Æû³µÍ£Ï£¬Æû³µÔ˶¯µÄ¾àÀëΪ50m£®
µãÆÀ ½â¾ö±¾ÌâµÄ¹Ø¼üÖªµÀСÆû³µÔÚ·´Ó¦Ê±¼äÄÚ×öÔÈËÙÖ±ÏßÔ˶¯£¬É²³µºó×öÔȼõËÙÖ±ÏßÔ˶¯£¬×¢Òâ²»ÄܺöÂÔ·´Ó¦Ê±¼äÄÚµÄλÒÆ£®
A£® | °ÑÏßȦÔÑÊýÔö¼Ó2±¶ | B£® | °ÑÏßȦÃæ»ýÔö¼Ó2±¶ | ||
C£® | °ÑÏßȦ°ë¾¶Ôö¼Ó2±¶ | D£® | ¸Ä±äÏßȦÓë´Å³¡·½ÏòµÄ¼Ð½Ç |
A£® | $\frac{5kQ}{4{l}^{2}}$£¬ÑØxÖáÕý·½Ïò | B£® | $\frac{5kQ}{4{l}^{2}}$£¬ÑØxÖḺ·½Ïò | ||
C£® | $\frac{3kQ}{4{l}^{2}}$£¬ÑØxÖḺ·½Ïò | D£® | $\frac{3kQ}{4{l}^{2}}$£¬ÑØxÖáÕý·½Ïò |
A£® | 4sÄ©µ½´ï×î¸ßµã£¬2sÄ©µ½´ï×î´ó¸ß¶ÈµÄÒ»°ë´¦ | |
B£® | 4sÄ©ËÙ¶ÈΪÁ㣬2sÄ©ËÙ¶ÈΪ³õËٶȵÄÒ»°ë | |
C£® | 8sĩλÒÆΪÁ㣬¼ÓËÙ¶ÈҲΪÁã | |
D£® | 8sĩλÒÆΪÁ㣬ËٶȴóСΪ40m/s |
A£® | ºÏÍâÁ¦¶ÔÓêµÎÒ»Ö±×öÕý¹¦ | |
B£® | ÓêµÎµÄËùÊܺÏÍâÁ¦µÄ¹¦ÂÊÏÈÔö´óºó¼õС | |
C£® | ÓêµÎÔÚt1ʱ¿ÌÒÔºó»úеÄÜÊغã | |
D£® | ÓêµÎËùÊÜ¿ÕÆø×èÁ¦±£³Ö²»±ä |