ÌâÄ¿ÄÚÈÝ
20£®Ò»Áмòгºá²¨ÑØxÖáÕý·½Ïò´«²¥£¬t=0ʱ¿ÌµÄ²¨ÐÎÈçͼÖÐʵÏßËùʾ£¬t=0.1sʱ¿ÌµÄ²¨ÐÎÈçͼÖÐÐéÏßËùʾ£®²¨Ô´²»ÔÚ×ø±êÔµãO£¬PÊÇ´«²¥½éÖÊÖÐÀë×ø±êÔµãxp=2.5m´¦µÄÒ»¸öÖʵ㣮ÔòÒÔÏÂ˵·¨ÕýÈ·µÄÊÇ£¨¡¡¡¡£©A£® | ÖʵãPµÄÕñ·ùΪ0.1 m | |
B£® | ²¨µÄƵÂÊ¿ÉÄÜΪ7.5 Hz | |
C£® | ²¨µÄ´«²¥ËٶȿÉÄÜΪ50 m/s | |
D£® | ÔÚt=0.1 sʱ¿ÌÓëPÏà¾à5 m´¦µÄÖʵãÒ»¶¨ÑØxÖáÕý·½ÏòÔ˶¯ | |
E£® | ÔÚt=0.1 sʱ¿ÌÓëPÏà¾à5 m´¦µÄÖʵã¿ÉÄÜÊÇÏòÉÏÕñ¶¯£¬Ò²¿ÉÄÜÊÇÏòÏÂÕñ¶¯ |
·ÖÎö ²¨ÑØxÖáÕý·½Ïò´«²¥£¬¸ù¾Ý²¨ÐεÄƽÒÆ·¨µÃµ½²¨µÄÖÜÆÚ¿ÉÄÜÖµ£¬Çó³öƵÂʵĿÉÄÜÖµºÍËٶȵĿÉÄÜÖµ£®¸ù¾Ýʱ¼äÓëÖÜÆڵĹØϵ£¬È·¶¨t=0.1ʱ¿ÌÖʵãPµÄλÖã¬ÅжÏÆäËٶȷ½Ïò£®
½â´ð ½â£º
A¡¢ÖʵãPµÄÕñ·ù¼´²¨µÄÕñ·ù£¬Îª0.1m£¬¹ÊAÕýÈ·£®
B¡¢²¨ÑØxÖáÕý·½Ïò´«²¥£¬Ôò¡÷t=nT+$\frac{T}{4}$£¬ÖÜÆÚΪT=$\frac{0.4}{4n+1}$s£¬ÆµÂÊΪf=$\frac{1}{T}$=$\frac{4n+1}{0.4}$=$\frac{20n+5}{2}$Hz£¬£¨n=0£¬1£¬2£¬3¡£©£¬ËùÒÔ²¨µÄƵÂÊ¿ÉÄÜΪ2.5Hz£¬12.5Hz£¬²»¿ÉÄÜΪ7.5 Hz£¬¹ÊB´íÎó£»
C¡¢²¨ËÙΪv=¦Ëf=4¡Á$\frac{20n+5}{2}$m/s=£¨40n+10£©m/s£¬ËùÒÔµ±n=1ʱ£¬v=50m/s£¬¹ÊCÕýÈ·£®
D¡¢ÔÚt=0.1 sʱ¿ÌÓëPÏà¾à5 m´¦µÄÖʵãÖ»ÄÜÉÏÏÂÕñ¶¯£¬²»¿ÉÄÜÑØxÖáÕý·½ÏòÔ˶¯£¬¹ÊE´íÎó£®
E¡¢ÓÉÓÚ²¨´«²¥µÄÖÜÆÚÐÔ£¬²¨ÑØxÖáÕý·½Ïò´«²¥£¬ÔÚt=0.1sʱ¿ÌÓëPÏà¸ô5m´¦µÄÖʵãÓëPµãÏà¾à1mµÄÖʵãÕñ¶¯Çé¿öÍêÈ«Ïàͬ£¬¼´¾àÔµãΪ3.5m»ò1.5mµÄÖʵãµÄÕñ¶¯Çé¿öÏàͬ£»¾ÝÐéÏß²¨ÐÎͼºÍ²¨ÏòÓÒ´«²¥¿ÉÖª£¬3.5mµÄÖʵãÑØyÖáÕý·½Ïò£¬¼´ÓëPÏà¾à5m´¦µÄÖʵãÒ²Ò»¶¨ÏòÉÏÕñ¶¯£»1.5mµÄÖʵãÑØyÖḺ·½Ïò£¬¼´ÓëPÏà¾à5m´¦µÄÖʵãÒ²Ò»¶¨ÏòÏÂÕñ¶¯£®¹ÊEÕýÈ·£®
¹ÊÑ¡£ºACE
µãÆÀ ±¾ÌâÔËÓò¨ÐεÄƽÒÆ·¨·ÖÎöʱ¼äÓëÖÜÆڵĹØϵ£¬È·¶¨²¨µÄÖÜÆÚ£¬ÊǾ³£²ÉÓõķ½·¨£®
A£® | Èô¿¨³µµÄ³õËÙ¶ÈΪ20m/s£¬ÆäËûÌõ¼þ¶¼²»±ä£¬Ôò¿¨³µ½«×²µ½Ð¡º¢ | |
B£® | ˾»ú·¢ÏÖÇé¿öºó£¬¿¨³µ¾¹ý3sͣϠ| |
C£® | ´Ó˾»ú·¢ÏÖÇé¿öµ½Í£ÏÂÀ´µÄ¹ý³ÌÖп¨³µµÄƽ¾ùËÙ¶ÈΪ11m/s | |
D£® | ˾»ú·¢ÏÖÇé¿öʱ£¬¿¨³µÓë¸ÃСº¢µÄ¾àÀëΪ31.5m |
A£® | µç×Ó´ÓAµ½BµÄ¹ý³ÌÖУ¬µç³¡Á¦¶ÔÆä×öÕý¹¦ | |
B£® | µç×Ó´ÓAµ½CµÄ¹ý³ÌÖУ¬µç³¡Á¦¶ÔÆä×ö¸º¹¦ | |
C£® | µç×Ó´ÓAµ½CµÄ¹ý³ÌÖУ¬ÆäµçÊÆÄÜÏÈÔö´óºó¼õС | |
D£® | µç×Ó´ÓAµ½CµÄ¹ý³ÌÖУ¬ÆäµçÊÆÄÜÏȼõСºóÔö´ó |
A£® | ·«´¬±±Æ«¶«30¡ã·½Ïòº½ÐУ¬ËٶȴóСΪ2v | |
B£® | ·«´¬¶«Æ«±±60¡ã·½Ïòº½ÐУ¬ËٶȴóСΪ$\sqrt{2}$v | |
C£® | ·«´¬¶«Æ«±±30¡ã·½Ïòº½ÐУ¬ËٶȴóСΪ2v | |
D£® | ·«´¬¶«Æ«ÄÏ60¡ã·½Ïòº½ÐУ¬ËٶȴóСΪ$\sqrt{2}$v |