做变速直线运动的汽车，通过第一个100m用了20s，通过第二个100m用了10s，求汽车在第一个100m内和第二个10
\u505a\u53d8\u901f\u76f4\u7ebf\u8fd0\u52a8\u7684\u6c7d\u8f66\uff0c\u901a\u8fc7\u7b2c\u4e00\u4e2a100m\u7528\u4e8620s\uff0c\u901a\u8fc7\u7b2c\u4e8c\u4e2a100m\u7528\u4e8610s\uff0c\u6c42\u6c7d\u8f66\u5728\u7b2c\u4e00\u4e2a100m\u5185\u548c\u7b2c\u4e8c\u4e2a10\u901a\u8fc7\u7b2c\u4e00\u4e2a100m\u7528\u4e8620s\uff0c\u6240\u4ee5\u6c7d\u8f66\u5728\u7b2c\u4e00\u4e2a100m\u5185\u7684\u5e73\u5747\u901f\u5ea6\u4e3a\uff1av1=s1t1\uff1d10020m/s\uff1d5m/s\u901a\u8fc7\u7b2c\u4e8c\u4e2a100m\u7528\u4e8610s\uff0c\u6240\u4ee5\u6c7d\u8f66\u5728\u7b2c\u4e8c\u4e2a100m\u5185\u7684\u5e73\u5747\u901f\u5ea6\u4e3a\uff1av2=s2t2\uff1d10010m/s\uff1d10m/s\u6c7d\u8f66\u5728\u8fd9200m\u5185\u7684\u5e73\u5747\u901f\u5ea6\u662f\uff1av=st\uff1d100+10020+10m/s\u22486.7m/s\u7b54\uff1a\u6c7d\u8f66\u5728\u7b2c\u4e00\u4e2a100m\u5185\u7684\u5e73\u5747\u901f\u5ea6\u4e3a5m/s\uff1b\u7b2c\u4e8c\u4e2a100m\u5185\u7684\u5e73\u5747\u901f\u5ea6\u4e3a10m/s\uff1b\u6c7d\u8f66\u5728\u8fd9200m\u5185\u7684\u5e73\u5747\u901f\u5ea6\u662f6.7m/s\uff0e
V\u5e73\u5747=\uff08x1+x2\uff09/(t1+t2\uff09=\uff08100+200\uff09/(10+20)=6.67m/s
通过第一个100m用了20s，所以汽车在第一个100m内的平均速度为：v1=
| s1 |
| t1 |
| 100m |
| 20s |
通过第二个100m用了10s，所以汽车在第二个100m内的平均速度为：
v2=
| s2 |
| t2 |
| 100m |
| 10s |
汽车在这200m内的平均速度是：
v=
| s |
| t |
| 200m |
| 20s+10s |
答：汽车在第一个100m内的平均速度为5m/s；
第二个100m内的平均速度为10m/s；
汽车在这200m内的平均速度是6.7m/s．
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绛旓細m/s="7" m/s鍙堝洜涓 = , AB = BC = , AC = 瑙ｅ緱:v A ="1" m/s,v B ="7" m/sa= m/s 2 ="3" m/s 2 .瑙ｆ硶涓:鐗╀綋鍋氬寑鍙橀熺洿绾胯繍鍔,婊¤冻螖s=aT 2 鎵浠= m/s 2 ="3" m/s 2 鐢眘 1 =v A t+ at 2 寰梫 A ="1" m/s.
