ÌâÄ¿ÄÚÈÝ
£¨2009?º£µíÇøһģ£©ÈçͼËùʾ£¬ÖÊÁ¿Îª70kgµÄ¹¤ÈËÕ¾ÔÚ°¶±ßͨ¹ýÒ»»¬ÂÖ×é´òÀÌÒ»¿é³ÁûÔÚË®³Øµ×²¿µÄʯ²Ä£¬¸Ã»¬ÂÖ×éÖж¯»¬ÂÖÖÊÁ¿Îª5kg£®µ±¹¤ÈËÓÃ120NµÄÁ¦À»¬ÂÖ×éµÄÉþ¶Ëʱ£¬Ê¯²ÄÈÔ³ÁÔÚË®µ×²»¶¯£®¹¤È˼ÌÐøÔö´óÀÁ¦½«Ê¯²ÄÀÆð£¬ÔÚÕû¸öÌáÉý¹ý³ÌÖУ¬Ê¯²ÄʼÖÕÒÔ0.2m/sµÄËÙ¶ÈÔÈËÙÉÏÉý£®ÔÚʯ²Ä»¹Ã»Óж³öË®Ãæ֮ǰ»¬ÂÖ×éµÄ»úеЧÂÊΪ¦Ç1£¬µ±Ê¯²ÄÍêȫ¶³öË®ÃæÖ®ºó»¬ÂÖ×éµÄ»úеЧÂÊΪ¦Ç2£®ÔÚʯ²ÄÍÑÀëË®³Øµ×²¿ÖÁÍêȫ¶³öË®ÃæµÄ¹ý³ÌÖУ¬µØÃæ¶ÔÈ˵ÄÖ§³ÖÁ¦µÄ×î´óÖµÓë×îСֵ֮±ÈΪ29£º21£®ÉþÖؼ°»¬ÂÖµÄĦ²Á¾ù¿ÉºöÂÔ²»¼Æ£¬Ê¯²ÄµÄÃܶȦÑʯ=2.5¡Á103kg/m3£¬È¡g=10N/kg£¬Çó£º
£¨1£©Óë´òÀÌÇ°Ïà±È£¬µ±ÈËÓÃ120NµÄÁ¦ÀÉþ¶Ëʱ£¬Ë®³Øµ×²¿¶Ôʯ²ÄµÄÖ§³ÖÁ¦±ä»¯Á˶àÉÙ£»
£¨2£©¦Ç1Óë¦Ç2µÄ±ÈÖµ£»
£¨3£©µ±Ê¯²ÄÍêȫ¶³öË®ÃæÒÔºó£¬ÈËÀÉþ×ӵŦÂÊ£®
£¨1£©Óë´òÀÌÇ°Ïà±È£¬µ±ÈËÓÃ120NµÄÁ¦ÀÉþ¶Ëʱ£¬Ë®³Øµ×²¿¶Ôʯ²ÄµÄÖ§³ÖÁ¦±ä»¯Á˶àÉÙ£»
£¨2£©¦Ç1Óë¦Ç2µÄ±ÈÖµ£»
£¨3£©µ±Ê¯²ÄÍêȫ¶³öË®ÃæÒÔºó£¬ÈËÀÉþ×ӵŦÂÊ£®
·ÖÎö£º£¨1£©ÈËÓÃ120NµÄÁ¦ÀÉþ¶ËÇ°ºó¶ÔÈ˺Ͷ¯»¬ÂÖÊÜÁ¦·ÖÎö¿ÉÖª³Øµ×²¿¶Ôʯ²ÄµÄÖ§³ÖÁ¦µÄ±ä»¯µÈÓÚ»¬ÂÖ×é϶ËÉþ×ÓÀʯ²ÄµÄÀÁ¦±ä»¯£¬½øÒ»²½Çó³öÆä´óС£®
£¨2£©¶Ô½þûºÍÍêȫ¶³öË®ÃæµÄʯ¿é¡¢µØÃæÉϵÄÈË·Ö±ðÊÜÁ¦·ÖÎö£¬¸ù¾ÝÁ¦µÄƽºâµÃ³öµÈʽ£»½þûʱʯ¿éµÄÌå»ýºÍÅÅ¿ªÒºÌåµÄÌå»ýÏàµÈ£¬¸ù¾ÝG=mg¡¢Ãܶȹ«Ê½ºÍ°¢»ùÃ×µÂÔÀí±íʾ³öÊܵ½µÄ¸¡Á¦£»¸ù¾ÝÏ໥×÷ÓÃÁ¦Ö®¼äµÄ¹ØϵÇó³öʯ¿éµÄÖØÁ¦ºÍÊܵ½µÄ¸¡Á¦£¬×îºó¸ù¾Ý¦Ç=
=
=
Çó³ö¦Ç1¡¢¦Ç2µÄ´óС£¬½øÒ»²½Çó³öÁ½ÕߵıÈÖµ£®
£¨3£©ÓÉW=FsºÍP=
¿ÉÖªÈËÀÉþ×ӵŦÂÊP=
=
=FnvÎÔÙÀûÓÃÒÑÖªÌõ¼þÇó³öÆä´óС£®
£¨2£©¶Ô½þûºÍÍêȫ¶³öË®ÃæµÄʯ¿é¡¢µØÃæÉϵÄÈË·Ö±ðÊÜÁ¦·ÖÎö£¬¸ù¾ÝÁ¦µÄƽºâµÃ³öµÈʽ£»½þûʱʯ¿éµÄÌå»ýºÍÅÅ¿ªÒºÌåµÄÌå»ýÏàµÈ£¬¸ù¾ÝG=mg¡¢Ãܶȹ«Ê½ºÍ°¢»ùÃ×µÂÔÀí±íʾ³öÊܵ½µÄ¸¡Á¦£»¸ù¾ÝÏ໥×÷ÓÃÁ¦Ö®¼äµÄ¹ØϵÇó³öʯ¿éµÄÖØÁ¦ºÍÊܵ½µÄ¸¡Á¦£¬×îºó¸ù¾Ý¦Ç=
WÓÐ |
W×Ü |
Gh |
FÀnh |
G |
FÀn |
£¨3£©ÓÉW=FsºÍP=
W |
t |
Fs |
t |
Fnh |
t |
½â´ð£º½â£º£¨1£©ÈËÓÃ120NµÄÁ¦ÀÉþ¶ËÇ°ºó¶ÔÈ˺Ͷ¯»¬ÂÖÊÜÁ¦·ÖÎöÈçͼ1¡¢2¡¢3Ëùʾ£º
³Øµ×²¿¶Ôʯ²ÄµÄÖ§³ÖÁ¦µÄ±ä»¯µÈÓÚ»¬ÂÖ×é϶ËÉþ×ÓÀʯ²ÄµÄÀÁ¦±ä»¯£º
¡÷FÖ§=T=3F-G¶¯=3¡Á120N-50N=310N£»
£¨2£©Ê¯²Ä½þûÔÚË®ÖÐʱ£¬¶Ô¶¯»¬ÂÖÊÜÁ¦·ÖÎöÈçͼ4Ëùʾ£º
ÈËÀÉþ¶ËµÄÁ¦FÀ1=
£¬
ÆäÖÐʯ²ÄËùÊܸ¡Á¦F¸¡=¦ÑË®gVÅÅ=
¦ÑË®£¬
ʯ²ÄÔÚ¿ÕÆøÖÐʱ£¬ÊÜÁ¦·ÖÎöÈçͼ5Ëùʾ£º
ÈËÀÉþ¶ËµÄÁ¦FÀ2=
£¬
Éèʯ²Ä½þûÔÚË®Öб»ÀÆðʱµØÃæ¶ÔÈ˵Ä×î´óÖ§³ÖÁ¦ÎªN1£¬Ê¯²ÄÔÚ¿ÕÆøÖÐʱµØÃæ¶ÔÈ˵Ä×îС֧³ÖÁ¦ÎªN2£¬
ËùÒÔ¶ÔÓÚʯ²Ä½þûÔÚË®ÖкÍÔÚ¿ÕÆøÖзֱðÓÐ
GÈË=N1+FÀ1¡ä£¬GÈË=N2+FÀ2¡ä£¬
ÒòΪFÀ1¡äÓëFÀ1´óСÏàµÈ£¬FÀ2¡äÓëFÀ2´óСÏàµÈ£¬ÇÒN1£ºN2=29£º21£¬
´úÈëÊý¾Ý½âµÃ£ºGʯ=1000N£¬F¸¡=400N£¬
ʯ²Ä½þûÔÚË®ÖÐʱ»¬ÂÖ×éµÄ»úеЧÂʦÇ1=
£¬
ʯ²ÄÍêȫ¶³öË®ÃæÖ®ºó»¬ÂÖ×éµÄ»úеЧÂʦÇ2=
£¬
ËùÒÔ
=
¡Á
=
¡Á
=
£»
£¨3£©ÈËÀÉþµÄ¹¦ÂÊ£ºP=FÀ2¡Ánv=£¨GÎï+G¶¯£©vÎï=£¨1000N+50N£©¡Á0.2m/s=210W£®
´ð£º£¨1£©Óë´òÀÌÇ°Ïà±È£¬µ±ÈËÓÃ120NµÄÁ¦ÀÉþ¶Ëʱ£¬Ë®³Øµ×²¿¶Ôʯ²ÄµÄÖ§³ÖÁ¦±ä»¯ÁË310N£»
£¨2£©¦Ç1Óë¦Ç2µÄ±ÈֵΪ63£º65£»
£¨3£©µ±Ê¯²ÄÍêȫ¶³öË®ÃæÒÔºó£¬ÈËÀÉþ×ӵŦÂÊΪ210W£®
³Øµ×²¿¶Ôʯ²ÄµÄÖ§³ÖÁ¦µÄ±ä»¯µÈÓÚ»¬ÂÖ×é϶ËÉþ×ÓÀʯ²ÄµÄÀÁ¦±ä»¯£º
¡÷FÖ§=T=3F-G¶¯=3¡Á120N-50N=310N£»
£¨2£©Ê¯²Ä½þûÔÚË®ÖÐʱ£¬¶Ô¶¯»¬ÂÖÊÜÁ¦·ÖÎöÈçͼ4Ëùʾ£º
ÈËÀÉþ¶ËµÄÁ¦FÀ1=
Gʯ+G¶¯-F¸¡ |
3 |
ÆäÖÐʯ²ÄËùÊܸ¡Á¦F¸¡=¦ÑË®gVÅÅ=
Gʯ |
¦Ñʯ |
ʯ²ÄÔÚ¿ÕÆøÖÐʱ£¬ÊÜÁ¦·ÖÎöÈçͼ5Ëùʾ£º
ÈËÀÉþ¶ËµÄÁ¦FÀ2=
Gʯ+G¶¯ |
3 |
Éèʯ²Ä½þûÔÚË®Öб»ÀÆðʱµØÃæ¶ÔÈ˵Ä×î´óÖ§³ÖÁ¦ÎªN1£¬Ê¯²ÄÔÚ¿ÕÆøÖÐʱµØÃæ¶ÔÈ˵Ä×îС֧³ÖÁ¦ÎªN2£¬
ËùÒÔ¶ÔÓÚʯ²Ä½þûÔÚË®ÖкÍÔÚ¿ÕÆøÖзֱðÓÐ
GÈË=N1+FÀ1¡ä£¬GÈË=N2+FÀ2¡ä£¬
ÒòΪFÀ1¡äÓëFÀ1´óСÏàµÈ£¬FÀ2¡äÓëFÀ2´óСÏàµÈ£¬ÇÒN1£ºN2=29£º21£¬
´úÈëÊý¾Ý½âµÃ£ºGʯ=1000N£¬F¸¡=400N£¬
ʯ²Ä½þûÔÚË®ÖÐʱ»¬ÂÖ×éµÄ»úеЧÂʦÇ1=
Gʯ-F¸¡ |
Gʯ+G¶¯-F¸¡ |
ʯ²ÄÍêȫ¶³öË®ÃæÖ®ºó»¬ÂÖ×éµÄ»úеЧÂʦÇ2=
Gʯ |
Gʯ+G¶¯ |
ËùÒÔ
¦Ç1 |
¦Ç2 |
Gʯ-F¸¡ |
Gʯ+G¶¯-F¸¡ |
Gʯ+G¶¯ |
Gʯ |
1000N-400N |
1000N+50N-400N |
1000N+50N |
1000N |
63 |
65 |
£¨3£©ÈËÀÉþµÄ¹¦ÂÊ£ºP=FÀ2¡Ánv=£¨GÎï+G¶¯£©vÎï=£¨1000N+50N£©¡Á0.2m/s=210W£®
´ð£º£¨1£©Óë´òÀÌÇ°Ïà±È£¬µ±ÈËÓÃ120NµÄÁ¦ÀÉþ¶Ëʱ£¬Ë®³Øµ×²¿¶Ôʯ²ÄµÄÖ§³ÖÁ¦±ä»¯ÁË310N£»
£¨2£©¦Ç1Óë¦Ç2µÄ±ÈֵΪ63£º65£»
£¨3£©µ±Ê¯²ÄÍêȫ¶³öË®ÃæÒÔºó£¬ÈËÀÉþ×ӵŦÂÊΪ210W£®
µãÆÀ£º±¾Ì⿼²éÁËÖØÁ¦¡¢Ãܶȹ«Ê½¡¢°¢»ùÃ×µÂÔÀí¡¢»úеЧÂÊ¡¢¹¦ÂʵȵļÆË㣬ÄѵãÊÇÇ󶯻¬ÂÖµÄÖØÁ¦ºÍʯ¿é½þûʱµÄ¸¡Á¦£¬¹Ø¼üÊǶԸ÷¸öÎïÌå½øÐÐÊÜÁ¦·ÖÎö£¬ÕâÊǽâ¾ö±¾ÌâµÄÖØÖÐÖ®ÖØ£®
Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿