ÌâÄ¿ÄÚÈÝ
Ò»ÖʵãÑØÖ±ÏßOx×ö¼ÓËÙÔ˶¯,ËüÀ뿪OµãµÄ¾àÀëxËæʱ¼ätµÄ±ä»¯¹ØϵΪx=5+2t3,ÆäÖÐxµÄµ¥Î»ÊÇm,tµÄµ¥Î»ÊÇs.ËüµÄËÙ¶ÈvËæʱ¼ät±ä»¯µÄ¹ØϵΪv=6t2,vµÄµ¥Î»ÊÇ m/s,tµÄµ¥Î»ÊÇs.Éè¸ÃÖʵãÔÚt=0µ½t="2" s¼äµÄƽ¾ùËÙ¶ÈΪv1,t="2" sµ½t="3" s¼äµÄƽ¾ùËÙ¶ÈΪv2,Ôò( )
A£®v1=12 m/s,v2=39 m/s |
B£®v1=8 m/s,v2=38 m/s |
C£®v1=12 m/s,v2=19.5 m/s |
D£®v1=8 m/s,v2=13 m/s |
B
¸ù¾ÝÖʵãÀ뿪OµãµÄ¾àÀëxËæʱ¼ätµÄ±ä»¯¹Øϵ,¿É¼ÆËãÈÎһʱ¿ÌÖʵã¾àOµãµÄ¾àÀëºÍ¸÷¶Îʱ¼äÄÚλÒÆ,ÔÙÓÉƽ¾ùËٶȵĶ¨Òåʽv=Çó¸÷¶Îʱ¼äÄÚµÄƽ¾ùËÙ¶È.½«t="0,t=2" s,t="3" s·Ö±ð´úÈëx=5+3t3,¿ÉµÃt=0ʱÖʵã¾àOµã¾àÀëx0="5" m,t="2" sʱÖʵã¾àOµã¾àÀëx2="21" m,t="3" sʱÖʵã¾àOµã¾àÀëx3="59" m,ËùÒÔÔÚt=0µ½t="2" s¼äµÄƽ¾ùËÙ¶ÈΪv1= m/s=8 m/s
ÔÚt="2" sµ½t="3" s¼äµÄƽ¾ùËÙ¶ÈΪ
v2= m/s=38 m/s
ËùÒÔÑ¡ÏîBÕýÈ·.
ÔÚt="2" sµ½t="3" s¼äµÄƽ¾ùËÙ¶ÈΪ
v2= m/s=38 m/s
ËùÒÔÑ¡ÏîBÕýÈ·.
Á·Ï°²áϵÁдð°¸
Ïà¹ØÌâÄ¿