一辆汽车沿平直公路从甲站开往乙站，起动加速度为2m/s2，加速行驶5秒，后匀速行驶2分钟，然后刹车，滑行5

\u4e00\u8f86\u6c7d\u8f66\u6cbf\u5e73\u76f4\u516c\u8def\u4ece\u7532\u7ad9\u51fa\u53d1\u5f00\u5f80\u4e59\u7ad9\uff0c\u8d77\u52a8\u52a0\u901f\u5ea6\u4e3a2m/s2\uff0c\u52a0\u901f\u884c\u9a765\u79d2\uff0c\u540e\u5300\u901f\u884c\u9a762\u5206\u949f\uff0c\u7136\u540e\u5239\u8f66\u505a

\uff081\uff09\u6c7d\u8f66\u505a\u5300\u52a0\u901f\u8fd0\u52a8\u65f6\u7684\u52a0\u901f\u5ea6a=2m/s2\uff0c\u52a0\u901f\u8fd0\u52a8\u7684\u65f6\u95f4\u4e3a5s\uff0c\u5219\u6c7d\u8f66\u5728\u5300\u52a0\u901f\u8fc7\u7a0b\u4e2d\u7684\u4f4d\u79fbx1\uff1d12at2\uff1d12\u00d72\u00d752m\uff1d25m\u6839\u636e\u901f\u5ea6\u65f6\u95f4\u5173\u7cfb\u53ef\u77e5\uff0c\u52a0\u901f5s\u540e\u6c7d\u8f66\u7684\u901f\u5ea6v=at=2\u00d75m/s=10m/s\uff0c\u5219\u6c7d\u8f66\u5728\u5300\u901f\u8fd0\u52a82\u5206\u949f\u65f6\u95f4\u5185\u7684\u4f4d\u79fbx2=vt=10\u00d7120m=1200m\u6c7d\u8f66\u505a\u5300\u51cf\u901f\u8fd0\u52a8\u7684\u4f4d\u79fbx3=50m\u6240\u4ee5\u7532\u4e59\u4e24\u7ad9\u95f4\u7684\u8ddd\u79bbx=x1+x2+x3=25+1200+50m=1275m\uff082\uff09\u6c7d\u8f66\u505a\u5300\u51cf\u901f\u8fd0\u52a8\u7684\u521d\u901f\u5ea6v0=10m/s\uff0c\u672b\u901f\u5ea6v=0\uff0c\u4ea7\u751f\u7684\u4f4d\u79fbx3=50m\u5219\u6839\u636e\u5300\u53d8\u901f\u76f4\u7ebf\u8fd0\u52a8\u7684\u5e73\u5747\u901f\u5ea6\u516c\u5f0f\u77e5\uff0c\u5300\u51cf\u901f\u8fd0\u52a8\u8fc7\u7a0b\u4e2d\u7684\u5e73\u5747\u901f\u5ea6.v3\uff1dv+v02\uff1d0+102m/s\uff1d5m/s\u6240\u4ee5\u5300\u51cf\u901f\u8fd0\u52a8\u8fc7\u7a0b\u65f6\u95f4t3\uff1dx3.v3\uff1d505s\uff1d10s\u6240\u4ee5\u6c7d\u8f66\u4ece\u7532\u81f3\u4e59\u6240\u7528\u65f6\u95f4t=t1+t2+t3=5+120+10s=135s\u5219\u6c7d\u8f66\u4ece\u7532\u5230\u4e59\u7684\u5e73\u5747\u901f\u5ea6.v\uff1dxt\uff1d1275135m/s\u22489.4m/s\u7b54\uff1a\uff081\uff09\u7532\u4e59\u4e24\u7ad9\u4e4b\u95f4\u7684\u8ddd\u79bb\u4e3a1275m\uff0e\uff082\uff09\u6c7d\u8f66\u4ece\u7532\u7ad9\u5230\u4e59\u7ad9\u7684\u5e73\u5747\u901f\u5ea6\u4e3a9.4m/s\uff0e

\u6839\u636ex=v0t+12at2\u5f97\u8d77\u52a8\u9636\u6bb5\u52a0\u901f\u8fd0\u52a8\u901a\u8fc7\u7684\u8ddd\u79bb\u4e3a\uff1ax=12\u00d72\u00d725\uff1d25m\uff0c\u5300\u901f\u8fd0\u52a8\u7684\u901f\u5ea6\u4e3a\uff1av=at=2\u00d75=10m/s\u6545\u7b54\u6848\u4e3a\uff1a25\uff0c10

解答：解：起动阶段行驶位移为：S₁=

1

2

at12
匀速行驶的速度为：V=at₁
匀速行驶的位移为：S₂=Vt₂  
刹车段的位移为：S₃=

V

2

t3
汽车从甲站到乙站的平均速度为：
V=

S1+S2+S3

t1+t2+t3

＝

25+1200+50

5+120+10

m/s＝

1275

135

m/s＝9.44m/s
答：汽车从甲站到乙站的平均速度为9.44m/s．

楂樹竴鐗╃悊,涓杈嗘苯杞︽部骞崇洿鍏矾浠庣敳绔欏紑寰涔绔,鍚姩鍔犻熷害涓2m/s²...
绛旓細杩欓鍙互鐢ㄤ綔鍥炬硶锛屾妸鍔犻熷拰鍖閫熼樁娈电殑V-t鍥句綔鍑猴紝鍙互姹傚緱姹借溅鍔犻熷拰鍖閫熼樁娈佃椹剁殑浣嶇Щ涓篨1=1/2*2*5^2+2*5*2*60=1225m,鍔犱笂婊戣浣嶇Щ锛屾讳綅绉讳负x=1275m銆傚埞杞︽粦琛屾椂闂村彲鐢50绫抽櫎浠ユ粦琛屽钩鍧囬熷害=10s.鎵浠姹借溅浠庣敳鍒颁箼骞冲潎閫熷害涓簐=1275/(10+5+120)=9.4444...m/s ...

涓杈嗘苯杞︽部骞崇洿鍏矾浠庣敳绔欏紑寰涔绔,鍚姩鍔犻熷害涓2 m/s2,鍔犻
绛旓細瑙ｏ細鍔犻5s鍚庣殑閫熷害锛歷=at1=2脳5=10m/s 鍔犻熻窛绂伙細x1=vt1/2=25m 鍖閫熻窛绂伙細x2=vt2 =10脳120= 1200m 鍑忛熻窛绂绘槸50绫筹紝璁惧噺閫熸椂闂存槸t3 x3=50=锕檝/2锕毭 t3=5t3 瑙ｅ緱锛歵3=10s 浜庢槸鎬荤殑骞冲潎閫熷害锛歏=锛坸1+x2+x3)/(t1+t2+t3)=1275/135=9.44m/s ...

(16鍒)涓杈嗘苯杞︽部骞崇洿鍏矾浠庣敳绔欏紑寰涔绔,鍚姩鍔犻熷害涓2 m/s 2 ,鍔...
绛旓細9.44 m/s 姹借溅鐨勮繍鍔ㄧず鎰忓浘濡傚浘鎵绀猴紝鍚姩闃舵琛岄┒浣嶇Щ涓猴細x 1 = 鈶犲寑閫熻椹剁殑閫熷害涓猴細v锛漚t 1 鈶″寑閫熻椹剁殑浣嶇Щ涓猴細x 2 锛漹t 2 鈶㈠埞杞﹂樁娈电殑浣嶇Щ涓猴細x 3 锛 t 3 鈶ｈ仈绔嬧憼鈶♀憿鈶ｅ洓寮忥紝鍙緱姹借溅浠庣敳绔欏埌涔绔欑殑骞冲潎閫熷害涓猴細 锛 锛 m/s锛 m/s鈮9.44 m/s.

涓杈嗘苯杞︽部骞崇洿鍏矾浠庣敳绔欏紑寰涔绔,鍚姩鍔犻熷害涓2m/s²,鍔犻熻椹2min...
绛旓細鍏堢畻鍔犻熻繃绋嬭蛋鐨勪綅绉25m.姝ゆ椂閫熷害涓10M/s鍙堜互姝ら熷害鍖閫熻蛋浜120s涓1200m.鎵浠ユ讳綅绉讳负25锛1200锛50=1275M 鍐嶇畻鍑忛熺殑鍔犻熷害涓猴紞1鎵鐢ㄦ椂闂翠负10S 鍙互寰楀嚭鎬绘椂闂翠负5锛120锛10=135s 鏈鍚庣敤鎬讳綅绉婚櫎浠ユ绘椂闂达紝寰楀嚭1275/135=9.4甯屾湜鑳藉浣犳湁鎵甯姪锛屾墦瀛椾笉鏄撶粰鍒嗗惂锛

涓杈嗘苯杞︽部骞崇洿鍏矾浠庣敳鍦寮寰涔鍦扮殑杩囩▼涓,鍓嶄袱灏忔椂鍐呯殑骞冲潎閫熷害鏄30k...
绛旓細鏄(30脳2+60脳1)梅(2+1)=40鍗冪背姣忓皬鏃

姹借溅娌鐫骞崇洿鐨鍏矾浠庣敳鍦寮寰涔鍦,(1)鑻ユ苯杞﹀湪鍓嶄竴鍗婅矾绋嬬殑骞冲潎閫熷害...
绛旓細锛1锛夎鐢蹭箼涓ゅ湴闂寸殑璺濈鏄2s锛屽垯鍓嶅崐娈典笌鍚庡崐娈电殑璺▼閮芥槸s锛屸埖v= s t 锛屸埓姹借溅鐨勮繍鍔ㄦ椂闂达細t 1 = s v 1 锛宼 2 = s v 2 锛屾荤殑杩愬姩鏃堕棿锛歵=t 1 +t 2 锛屽叏绋嬬殑骞冲潎閫熷害锛 . v = 2s t = 2s s v 1 + ...

姹借溅娌鐫骞崇洿鐨鍏矾浠庣敳鍦寮寰涔鍦,(1)鑻ユ苯杞﹀湪鍓嶄竴鍗婅矾绋嬬殑骞冲潎閫熷害...
绛旓細锛1锛夎鐢蹭箼涓ゅ湴闂寸殑璺濈鏄2s锛屽垯鍓嶅崐娈典笌鍚庡崐娈电殑璺▼閮芥槸s锛屸埖v=st锛屸埓姹借溅鐨勮繍鍔ㄦ椂闂达細t1=sv1锛宼2=sv2锛屾荤殑杩愬姩鏃堕棿锛歵=t1+t2锛屽叏绋嬬殑骞冲潎閫熷害锛.v=2st=2ssv1+sv2=2v1v2v1+v2锛涳紙2锛夊墠涓鍗婅矾绋嬪拰鍚庝竴鍗婅矾绋嬫墍鐢ㄦ椂闂寸浉鍚岋紝鍒檛1=t2=sv1=sv2锛屽垯v1=v2锛屽叏绋嬬殑杩愬姩鏃堕棿锛歵鈥=2...

鍏叡姹借溅浠庣敳绔欐部骞崇洿鍏矾寮寰涔绔
绛旓細鍒硅溅鍜屽姞閫熼兘鍙互鐢ㄥ寑鍔犻熷叕寮忔潵璁＄畻鏈鐭埞杞︽椂闂村唴璧板嚭鐨勮窛绂 S3=0+27.5m锛 鍒欏彲鐭ュ叕鍏辨苯杞﹀湪鏈澶ч熷害涓嬪彲浠ヨ杩涚殑璺濈S2=1200-37.5-27.5=1135m锛屽搴斿湪鏈澶ч熷害涓嬪寑閫熻繍琛屾椂闂磘2=1135/15=75.66s 4锛夌患涓婏紝鍙緱鐭ュ叕鍏姹借溅浠庣敳绔欏紑寰涔绔欑殑鏈鐭椂闂碩=t1+t2+t3=5+75+3 =83.66 s ...

姹借溅娌垮钩鐩村叕璺粠鐢鍦寮寰涔鍦,涓ゅ湴鐩歌窛90km,寮濮嬫椂姹借溅浠10m/s鐨勯熷害...
绛旓細锛1锛夌敱v=st寰楋細寮濮嬭椹剁殑璺▼锛歴1=v1t1=10m/s脳1.5脳3600s=54000m锛涘墿浣欒矾绋嬶細s2=s-s1=90000m-54000m=36000m=36km锛寁2=s2t2=36km45脳160h=48km/h锛庯紙2锛夆埖t=t1+t2=1.5h+45脳160h=2.25h锛屸埓鏁翠釜璺▼姹借溅鐨勫钩鍧囬熷害v=st=90km2.25h=40km/h锛庣瓟锛氬悗鏉ユ苯杞﹀簲浠48km/h鐨...

姹借溅娌垮钩鐩村叕璺粠鐢鍦寮寰涔鍦,涓ゅ湴鐩歌窛90km,寮濮嬫椂姹借溅浠10m/s鐨勯熷害...
绛旓細锛1锛塿1=10m/s=36km/h锛屸埖v=st锛屸埓鍓嶆鐨勮矾绋媠1=v1t1=36km/h脳1h=36km锛涳紙2锛変綑涓嬬殑璺▼s2=s-s1=90km-36km=54km锛宼2=45min=0.75h锛姹借溅鐨勯熷害v2=s2t2=54km0.75h=72km/h锛涚瓟锛氾紙1锛夋苯杞﹀湪鍓嶆鏃堕棿琛岄┒鐨勮矾绋嬫槸36km锛庯紙2锛夋苯杞﹀湪浣欎笅鐨勮矾绋嬩笂鐨勮椹堕熷害鏄72km/h锛