ÌâÄ¿ÄÚÈÝ
6£®ÈçͼËùʾ£¬ÖÊÁ¿ÎªM=2kgµÄÔ²»·×´µ¯ÐÔÎï¿éA£¨¿ÉÊÓΪÖʵ㣩£¬Ì×ÔÚÖÊÁ¿Îªm=1kg¡¢³¤L=6.9mµÄÖ±Á¢¾ùÔȸËBÉ϶ˣ¬A¡¢B¼äµÄ×î´ó¾²Ä¦²ÁÁ¦ÊÇf=mg£¬ÇÒ»¬¶¯Ä¦²ÁÁ¦Óë×î´ó¾²Ä¦²ÁÁ¦´óСÏàµÈ£¬¸Ë϶˾àµØÃæ¸ßH=0.8m£¬ÖØÁ¦¼ÓËÙ¶ÈΪg=10m/s2£¬½«¸ËºÍÎï¿é¾ù´Ó¾²Ö¹¿ªÊ¼ÊÍ·Å£¬¸Ë϶ËÓëµØÃæÅöײºóÒÔÔËÙÂÊ·´µ¯£¬²»¼ÆÅöײʱ¼ä¼°¿ÕÆø×èÁ¦£¬Ç󣺣¨1£©¸ËµÚÒ»´Î¸ÕÒª´¥µØʱËٶȵĴóСv0£»
£¨2£©Îï¿éÔÚ¸ËÉÏÔ˶¯µÄʱ¼ä£»
£¨3£©Îï¿é¸ÕÒª´¥µØʱËٶȴóС£®
·ÖÎö £¨1£©¸ËµÚÒ»´ÎÂäµØÇ°¸ËÓëÎï¿é¶¼×ö×ÔÓÉÂäÌåÔ˶¯£¬Ó¦ÓÃÔȱäËÙÖ±ÏßÔ˶¯µÄËÙ¶ÈλÒƹ«Ê½¿ÉÒÔÇó³ö¸ËµÚÒ»´ÎÂäµØµÄËٶȣ®
£¨2£©Ó¦ÓÃÅ£¶ÙµÚ¶þ¶¨ÂÉÇó³öÎï¿éµÄ¼ÓËٶȣ¬È»ºóÓ¦ÓÃÔȱäËÙÖ±ÏßÔ˶¯µÄλÒƹ«Ê½Çó³öÎï¿éÔÚ¸ËÉÏÔ˶¯µÄʱ¼ä£®
£¨3£©Ó¦ÓÃÔȱäËÙÖ±ÏßÔ˶¯µÄËٶȹ«Ê½Çó³öÎï¿é´¥µØʱµÄËٶȴóС£®
½â´ð ½â£º£¨1£©¸ËµÚÒ»´Î¸ÕÒª´¥µØÇ°£¬¸ËºÍÎï¿é×ö×ÔÓÉÂäÌåÔ˶¯£¬
ÓÉÔȱäËÙÖ±ÏßÔ˶¯µÄËÙ¶ÈλÒƹ«Ê½µÃ£º${v}_{0}^{2}=2gH$£¬
½âµÃ£ºv0=$\sqrt{2gH}$=$\sqrt{2¡Á10¡Á0.8}$=4m/s£¬
Îï¿é×ÔÓÉÏÂÂäµÄʱ¼ä£ºt1=$\frac{{v}_{0}}{g}$=$\frac{4}{10}$=0.4s£»
£¨2£©¸ËµÚÒ»´ÎÓëµØÃæÅöײºó£¬Îï¿éÏòÏÂ×öÔȼÓËÙÖ±ÏßÔ˶¯£¬
¸ËÏÈÏòÉÏ×öÔȼõËÙÖ±ÏßÔ˶¯£¬ËٶȱäΪÁãºóÔÙÏòÏÂ×öÔȼÓËÙÖ±ÏßÔ˶¯£¬
Èç´Ë·´¸´£¬Îï¿éÂäµØÇ°Îï¿éÒ»Ö±ÔÚ¸ËÉÏÔ˶¯£¬Îï¿éµÄ¼ÓËٶȣº
a=$\frac{Mg-f}{M}$=$\frac{Mg-mg}{M}$=$\frac{2¡Á10-1¡Á10}{2}$=5m/s2£¬
¸ËµÚÒ»´ÎÂäµØµ½Îï¿éÂäµØ¹ý³ÌÎï¿éÒ»Ö±ÏòÏÂ×öÔȼÓËÙÖ±ÏßÔ˶¯£¬
ÓÉÔȱäËÙÔ˶¯µÄλÒƹ«Ê½µÃ£ºL=v0t2+$\frac{1}{2}$at22£¬
¼´£º6.9=4t2+$\frac{1}{2}$¡Á5¡Át22£¬
½âµÃ£ºt2=0.84s£¬
Îï¿éÔÚ¸ËÉϵÄÔ˶¯Ê±¼ä£ºt=t1+t2=1.24s£»
£¨3£©Îï¿é¸ÕÒª´¥µØʱµÄËٶȴóС£º
v=v0+at2=4+5¡Á0.84=8.2m/s£»
´ð£º£¨1£©¸ËµÚÒ»´Î¸ÕÒª´¥µØʱËٶȵĴóСv0Ϊ4m/s£»
£¨2£©Îï¿éÔÚ¸ËÉÏÔ˶¯µÄʱ¼äΪ1.24s£»
£¨3£©Îï¿é¸ÕÒª´¥µØʱËٶȴóСΪ8.2m/s£®
µãÆÀ ±¾Ì⿼²éÁËÇóËÙ¶ÈÓëÔ˶¯Ê±¼äÎÊÌ⣬±¾ÌâÎïÌåµÄÔ˶¯¹ý³Ì¸´ÔÓ£¬ÄѶȽϴ󣬷ÖÎöÇå³þÎïÌåµÄÔ˶¯¹ý³ÌÓëÊÜÁ¦Çé¿öÊǽâÌâµÄÇ°ÌáÓë¹Ø¼ü£¬Ó¦ÓÃÅ£¶ÙµÚ¶þ¶¨ÂÉÓëÔ˶¯Ñ§¹«Ê½¿ÉÒÔ½âÌ⣮
A£® | ½ðÊôÇòÉÏÉý´©Ô½´Å³¡¹ý³ÌÖУ¬ËùÊÜ°²ÅàÁ¦·½ÏòʼÖÕÏòÏ | |
B£® | ½ðÊôÇòÏÂÂä´©Ô½´Å³¡¹ý³ÌÖУ¬¼ÓËÙ¶ÈÖð½¥Ôö´ó | |
C£® | ½ðÊôÇòÉÏÉýºÍÏÂÂä´©Ô½´Å³¡¹ý³ÌÖУ¬°²ÅàÁ¦×ö¹¦ÏàµÈ | |
D£® | ÊôÇòÉÏÉýºÍÏÂÂä´©Ô½´Å³¡¹ý³ÌÖУ¬²úÉúµÄ½¹¶úÈÈÏàµÈ |
A£® | 52.8kW•h | B£® | 26.4kW•h | C£® | 39.6kW•h | D£® | 79.2kW•h |
A£® | µÚ1sÄ©ÖʵãµÄËٶȸı䷽Ïò | B£® | µÚ2sÄ©ÖʵãµÄ¼ÓËٶȸı䷽Ïò | ||
C£® | µÚ3sÄ©ºÍµÚ5sÄ©ÖʵãµÄλÖÃÏàͬ | D£® | µÚ4sÄ©ÖʵãµÄλÒÆΪÁã |