一辆汽车沿平直公路从甲站开往乙站,起动加速度为2m/s 2 ,加速行驶5秒,后匀速行驶2分钟,然后刹车,匀
\u4e00\u8f86\u6c7d\u8f66\u6cbf\u5e73\u76f4\u516c\u8def\u4ece\u7532\u7ad9\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\u6709\u6728\u6709\u6ed1\u884c\u591a\u5c11\u79d2?
\u89e3\uff1aS=1/2at1^2+120at2+50=1275m
v=at1=10 t'=S'/v/2=10s t\u603b=5+120+10s=135s
\u7b54\uff1a\u7532\u3001\u4e59\u4e24\u7ad9\u7684\u8ddd\u79bb\u4e3a1275m\uff0c\u6c7d\u8f66\u4ece\u7532\u7ad9\u5230\u4e59\u7ad9\u6240\u7528\u65f6\u95f4\u4e3a135s
起动阶段行驶位移为:S 1 =
匀速行驶的速度为:V=at 1 =10m/s 匀速行驶的位移为:S 2 =Vt 2 =10×120m=1200m 所以甲站到乙站之间的距离为25+1200+50m=1275m 故答案为:1275 |
绛旓細鍖鍑忛熺洿绾胯繍鍔:Vt=0,V0=10m/s,S3=50, (Vt)^2-(V0)^2=-2as 鍥犱负鏄噺閫熻繍鍔紝鎵浠鍙栬礋鍊 0-10^2=-2a*50 a=1m/s^2 锛 鍥犱负 Vt=V0-at 锛0=10-at 锛 t=10s S鎬=S1+S2+S3=25+1200+50=1275m t鎬诲氨鏄笁涓樁娈垫墍鐢ㄧ殑鏃堕棿鎬诲拰锛氬嵆t鎬=5+120+10=135s 鍏...
绛旓細渚嬮 涓杈嗘苯杞︽部骞崇洿鍏矾浠庣敳绔欏紑寰涔绔欙紝璧峰姩鏃跺姞閫熷害涓2m/s2锛屽姞閫熻椹朵簡5绉掞紝杈惧埌绋冲畾閫熷害鍚庡張鍖閫熻椹朵簡2鍒嗛挓锛岀劧鍚庡埞杞︼紝婊戣50m锛屾濂藉埌杈句箼绔欙紝姹傛苯杞︿粠鐢茬珯鍒颁箼绔欑殑鎬绘椂闂磘銆佹讳綅绉粁鍜屾暣涓繃绋嬫苯杞︾殑骞冲潎閫熷害锛熷垎鏋愶細姹借溅浠庣敳绔欏紑寰涔欑珯鐨勬暣涓繃绋嬬殑杩愬姩鍙互鍒嗕负涓変釜闃舵锛屽嵆锛氫竴寮濮嬬殑鍒濋...
绛旓細瑙g瓟锛氳В锛氳捣鍔ㄩ樁娈佃椹朵綅绉讳负锛歋1=12at12鍖閫熻椹剁殑閫熷害涓猴細V=at1鍖閫熻椹剁殑浣嶇Щ涓猴細S2=Vt2 鍒硅溅娈电殑浣嶇Щ涓猴細S3=V2t3姹借溅浠庣敳绔欏埌涔欑珯鐨勫钩鍧囬熷害涓猴細V=S1+S2+S3t1+t2+t3锛25+1200+505+120+10m/s锛1275135m/s锛9.44m/s绛旓細姹借溅浠庣敳绔欏埌涔欑珯鐨勫钩鍧囬熷害涓9.44m/s锛
绛旓細璧峰姩闃舵琛岄┒浣嶇Щ涓猴細S 1 = 1 2 at 1 2 = 1 2 脳2脳25m=25m 鍖閫熻椹剁殑閫熷害涓猴細V=at 1 =10m/s鍖閫熻椹剁殑浣嶇Щ涓猴細S 2 =Vt 2 =10脳120m=1200m鎵浠鐢茬珯鍒颁箼绔欎箣闂寸殑璺濈涓25+1200+50m=1275m鏁呯瓟妗堜负锛1275 ...
绛旓細瑙o細S=1/2at1^2+120at2+50=1275m v=at1=10 t'=S'/v/2=10s t鎬=5+120+10s=135s 绛旓細鐢层佷箼涓ょ珯鐨勮窛绂讳负1275m锛姹借溅浠庣敳绔欏埌涔欑珯鎵鐢ㄦ椂闂翠负135s
绛旓細1 銆 涓杈嗘苯杞︽部骞崇洿鍏矾浠庣敳鎴寮寰涔绔,鍚姩鍔犻熷害涓2绫虫瘡浜屾鏂瑰锛屽姞閫熷害褰㈠紡5绉掞紝鍚庡寑閫熷舰寮2鍒嗛挓锛岀劧鍚庡埞杞︼紝婊戣50绫筹紝姝eソ鍒拌揪涔欑珯锛屾眰姹借溅浠庣敳鎴鍒颁箼绔欑殑骞冲潎閫熷害銆傚姞閫燂細S1=1/2at^2=1/2*2*25=25m,v1=at=2*5=10m/s 鍖閫熻繍鍔細s2=v1t2=10*2*60=1200m 鍒硅溅锛歵3=s3/(v1...
绛旓細鍖閫熺殑浣嶇Щx2=vt2=10脳120m=1200m锛屽垯鐢蹭箼涓ょ珯鐨勮窛绂粁=x1+x2+x3=25+1200+50m=1275m锛庢牴鎹畑3锛漹2t3寰楋紝鍖鍑忛熻繍鍔ㄧ殑鏃堕棿t3锛2x3v锛2脳5010s锛10s锛屽垯姹借溅浠庣敳绔欏埌涔绔欑殑鏃堕棿t=t1+t2+t3=5+120+10s=135s锛庣瓟锛氱敳銆佷箼涓ょ珯鐨勮窛绂讳负1275m锛屾苯杞︿粠鐢茬珯鍒颁箼绔欑殑鏃堕棿涓135s锛
绛旓細瑙o細姹借溅鍚姩闃舵琛岄┒浣嶇Щ涓猴細 鍖閫熻椹剁殑閫熷害涓猴細v=at 1 鍖閫熻椹剁殑浣嶇Щ涓猴細x 2 =vt 2 鍒硅溅闃舵鐨勪綅绉讳负锛 鑱旂珛鍥涘紡鍙緱姹借溅浠庣敳绔欏埌涔绔欑殑骞冲潎閫熷害涓猴細 =
绛旓細璧峰姩闃舵琛岄┒浣嶇Щ涓猴細S 1 = 1 2 a t 1 2 鍖閫熻椹剁殑閫熷害涓猴細V=at 1 鍖閫熻椹剁殑浣嶇Щ涓猴細S 2 =Vt 2 鍒硅溅娈电殑鏃堕棿涓猴細S 3 = V 2 t 3 姹借溅浠庣敳绔欏埌涔绔欑殑骞冲潎閫熷害涓猴細V= S 1 + S 2 + S 3 t 1 + t 2 + t...
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