一辆汽车在笔直的公路上做匀变速直线运动。该公路每隔15m安置一个路标。汽车通过前两个相邻路标AB用
\u4e00\u8f86\u6c7d\u8f66\u5728\u7b14\u76f4\u7684\u516c\u8def\u4e0a\u505a\u5300\u53d8\u901f\u76f4\u7ebf\u8fd0\u52a8\uff0c\u8be5\u516c\u8def\u6bcf\u969415m\u5b89\u7f6e\u4e00\u4e2a\u8def\u6807\uff0c\u4f9d\u6b21\u4e3aA\u3001B\u3001C\uff0c\u6c7d\u8f66\u901a\u8fc7AB\u4e24\u76f8\u90bb\u8bbe\u6c7d\u8f66\u5728A\u70b9\u7684\u901f\u5ea6\u4e3aV1\uff0c\u5728B\u70b9\u7684\u901f\u5ea6\u4e3aV2,\u5728C\u70b9\u7684\u901f\u5ea6\u4e3aV3.
AB\u6bb5\u7684\u5e73\u5747\u901f\u5ea6\u662f(V1+V2)/2
BC\u6bb5\u7684\u5e73\u5747\u901f\u5ea6\u662f(V2+V3)/2
AC\u6bb5\u7684\u5e73\u5747\u901f\u5ea6\u662f(V1+V3)/2
\u6240\u4ee5\u6709
[(V1+V2)/2]*2=15
[(V2+V3)/2]*3=15
[(V1+V3)/2]*(2+3)=30
\u89e3\u5f97
V1=17/2 m/s V2=13/2 m/s V3=7/2 m/s
\u5148\u7528\u8ddd\u79bbS=V\u3002\u00b7t+a\u00b7t²/2\u516c\u5f0f\uff1b\u6c42\u51fa\u521d\u901f\u5ea6V\u3002(\u5373\uff1a\u901f\u5ea6A)\u548c\u52a0\u901f\u5ea6a\uff1b\u518d\u6c42B\u3001C\u7684\u901f\u5ea6\u3002
15=\u901f\u5ea6A\u00b72+a\u00b72²/2\uff1b\u5f97\uff1a2\u00b7\u901f\u5ea6A+2a=15 \u2460\u5f0f
30=\u901f\u5ea6A\u00b75+a\u00b75²/2\uff1b\u5f97\uff1a5\u00b7\u901f\u5ea6A+12.5a=30 \u2461\u5f0f
\u2460\u5f0f\u548c \u2461\u5f0f\u8054\u7acb\u89e3\u5f97\uff1a\u901f\u5ea6A=8.5 m/s\uff1b
\u52a0\u901f\u5ea6a=-1 m/s²\uff1b
\u6240\u4ee5\uff0c\u901f\u5ea6B=\u901f\u5ea6A+at=8.5+(-1) \u00d72=6.5 m/s\uff1b
\u901f\u5ea6C=\u901f\u5ea6A+at=8.5+(-1) \u00d75=3.5 m/s\uff1b
\u6216\uff0c\u9a8c\u7b97\u4e00\u4e0b\uff1a
\u901f\u5ea6C=\u901f\u5ea6B+at=6.5+(-1) \u00d73=3.5 m/s\uff1b
\u56e0\u6b64\uff1a\u901f\u5ea6A=8.5 m/s\uff1b
\u901f\u5ea6B=6.5 m/s\uff1b
\u901f\u5ea6C=3.5 m/s\uff1b
绛旓細鍏堢敤璺濈S=V銆偮穞+a路t²/2鍏紡锛涙眰鍑哄垵閫熷害V銆(鍗筹細閫熷害A)鍜屽姞閫熷害a锛涘啀姹侭銆丆鐨勯熷害銆15=閫熷害A路2+a路2²/2锛涘緱锛2路閫熷害A+2a=15 鈶犲紡 30=閫熷害A路5+a路5²/2锛涘緱锛5路閫熷害A+12.5a=30 鈶″紡 鈶犲紡鍜 鈶″紡鑱旂珛瑙ｅ緱锛氶熷害A=8.5 m/s锛涘姞閫熷害a=-1 ...
绛旓細2.涓杈嗘苯杞﹀湪绗旂洿鐨勫叕璺笂鍋氬寑鍙橀鐩寸嚎杩愬姩锛岃鍏矾姣忛殧15m瀹夌疆涓涓矾鏍囷紝姹借溅閫氳繃AB涓ょ浉閭荤殑璺爣鐢ㄤ簡2s锛岄氳繃BC璺爣鐢ㄤ簡3s锛屾眰姹借溅鍒嗗埆閫氳繃A.B.C涓変釜璺爣鏃剁殑閫熷害 瑙ｆ硶涓:Vt=Vo+at Vb=Va+2a Vc=Va+(2+3)a=Va+5a 鍦ˋB鍜孉C娈靛钩鍧囬熷害鍒嗗埆涓 V1=(Va+Vb)/2=(Va+Va+2a)/2=Va+a V2...
绛旓細鍏堢敤璺濈S=V.路t+a路t²/2鍏紡锛涙眰鍑哄垵閫熷害V.(鍗筹細閫熷害A)鍜屽姞閫熷害a锛涘啀姹侭銆丆鐨勯熷害.15=閫熷害A路2+a路2²/2锛涘緱锛2路閫熷害A+2a=15 鈶犲紡 30=閫熷害A路5+a路5²/2锛涘緱锛5路閫熷害A+12.5a=30 鈶″紡 鈶犲紡鍜 鈶″紡鑱旂珛瑙ｅ緱锛氶熷害A=8.5 m/s锛涘姞閫熷害a=-1 m/s...
绛旓細璁姹借溅鍦ˋ鐐圭殑閫熷害涓篤1锛屽湪B鐐圭殑閫熷害涓篤2,鍦–鐐圭殑閫熷害涓篤3.AB娈电殑骞冲潎閫熷害鏄(V1+V2)/2 BC娈电殑骞冲潎閫熷害鏄(V2+V3)/2 AC娈电殑骞冲潎閫熷害鏄(V1+V3)/2 鎵浠ユ湁 [(V1+V2)/2]*2=15 [(V2+V3)/2]*3=15 [(V1+V3)/2]*(2+3)=30 瑙ｅ緱 V1=17/2 m/s V2=13/2 m/s V...
绛旓細璁姹借溅缁忚繃ABC涓夌偣鐨勯熷害鍒嗗埆涓猴細VA锛孷B锛孷C锛庡姞閫熷害涓篴鐢鍖鍙橀鐩寸嚎杩愬姩鐨勮寰嬪彲寰楋細XAB锛漋At1+12at12 锛1锛塜BC锛漋Bt2+12at22 锛2锛塚B=VA+at1 锛3锛塚C=VB+at2 锛4锛変唬鍏ユ暟鍊兼眰瑙ｅ緱锛歏A=100m/sVB=2503m/sVC=1753m/s绛旓細姹借溅閫氳繃A銆丅銆丆涓変釜璺爣鏃剁殑閫熷害鍒嗗埆涓100m/s锛2...
绛旓細璁姹借溅缁忚繃A鐐规椂鐨勯熷害涓簐1锛屽姞閫熷害涓篴锛屽AB娈佃繍鍔ㄧ敱浣嶇Щ鏃堕棿鍏紡寰楋細x1锛漹1t1+12at21鍚岀悊瀵笰C娈佃繍鍔ㄦ牴鎹綅绉绘椂闂村叕寮忓緱锛歺2锛漹1t2+12at22鍏朵腑x1=15m锛寈2=30m锛宼1=2s锛宼2=5s鑱旂珛鏂圭▼鈶犫憽骞跺甫鍏ユ暟鎹緱锛歛=-1m/s2锛寁1=8.5m/s鏁呯瓟妗堜负锛1m/s2 8.5 m/s ...
绛旓細鍔犻熷害涓篴锛岄偅涔堝湪B鐐圭殑閫熷害涓篤2=V1+2a锛屽湪C鐐圭殑閫熷害涓篤3=V2+3a鎴戜滑鐭ラ亾锛氬仛 鐨勭墿浣擄細浣嶇ЩS=Vt+1/2at*t鍥犳锛氭垜浠彲浠ュ緱鍑哄涓嬬瓑寮忥細2V1+2a=15m 3V2+9/2a=15m V 2=V1+2a V3=V2+3a鐢辨寰楋細V1=17/2 m/s a=-1m/s*s V2=13/2 鍙兘浣犵湅涓嶆噦 ...
绛旓細涓杈嗘苯杞﹀湪绗旂洿鐨勫叕璺笂鍋氬寑鍙橀鐩寸嚎杩愬姩銆傝鍏矾姣忛殧15m瀹夌疆涓涓矾鏍囥傛苯杞﹂氳繃鍓嶄袱涓浉閭昏矾鏍嘇B鐢 浜2s,閫氳繃BC涓よ矾鏍嚶风敤浜3S銆傛眰姹借溅閫氳繃A.B.C.涓変釜璺爣鏃剁殑閫熷害?... 浜2s,閫氳繃BC涓よ矾鏍嚶风敤浜3S銆傛眰姹借溅閫氳繃A.B.C.涓変釜璺爣鏃剁殑閫熷害? 灞曞紑 鎴戞潵绛 ...
绛旓細瑙ｏ細宸茬煡s=15m锛宼1=2s,t2=3s銆傝A鐐瑰垵閫熷害涓簐锛屽姞閫熷害涓篴 缁忚繃AB浣嶇Щ锛歴=v*t1+½ a t1²锛涚粡杩嘇C浣嶇Щ锛2s=v*锛坱1+t2)+½ a (t1+t2)²涓や釜鏈煡鏁颁袱鏉℃柟绋嬪彲瑙ｅ緱v=8.5m/s, a=-1m/s²鈥斺斺斾笉鏄庣櫧杩介棶鍚 ...
绛旓細鍥犱负鏄鍖鍙橀杩愬姩锛屾墍浠B鐨勫钩鍧囬熷害涓篤ab=s/t=15/2=7.5m/s锛孊C鐨勫钩鍧囬熷害Vbc=s/t=15/3=5m/s 鑰孉B骞冲潎閫熷害鍒癇C骞冲潎閫熷害鎵鐢ㄧ殑鏃堕棿鏄2.5s锛屾墍浠ュ姞閫熷害a=锛7.5-5锛/2.5=1m/s^2. 鐢辨鍙煡 Va=8.5m/s Vb=6.5m/s Vc=3.5m/s Vab銆乂bc鐨勫钩鍧囬熷害涔熷氨鏄疭ab銆丼bc鎵鐢ㄦ椂闂寸殑涓鍗...
