一个做匀变速直线运动的质点,从某一时刻开始在第一个2 s内通过的位移是8 m,在第二个2 s内通过的位移是20
\u4e00\u4e2a\u505a\u5300\u53d8\u901f\u76f4\u7ebf\u8fd0\u52a8\u7684\u8d28\u70b9\uff0c\u4ece\u67d0\u4e00\u65f6\u523b\u5f00\u59cb\uff0c\u5728\u7b2c\u4e00\u4e2a2S\u5185\u901a\u8fc7\u7684\u4f4d\u79fb\u662f8\u7c73\uff0c\u5728\u7b2c\u4e8c\u4e2a2S\u5185\u901a\u8fc7\u7684\u4f4d\u79fb\u662f20s=v0t+1/2at*t
8=v0*2+1/2a2*2
20+8=v0*4+1/2a4*4
\u8054\u7acb\u65b9\u7a0b\u53ef\u89e3\u5f97a=3 v0=1
\u8bbe\u4ecet\u65f6\u523b\u5f00\u59cb\uff0ct\u65f6\u523b\u7684\u901f\u5ea6\u4e3aV1\uff0c\u7b2c\u4e00\u4e2a2s\u5185\u901a\u8fc7\u7684\u4f4d\u79fb\u662f8m,\u52192V1+\uff081/2\uff09a(2^2)=8
\u5373V1+a=4
\u8bbe\u7b2c\u4e00\u4e2a2s\u540e\u7684\u901f\u5ea6\u4e3aV2
\u5219V2=V1+2a
\u56e0\u5728\u7b2c\u4e8c\u4e2a2s\u5185\u901a\u8fc7\u7684\u4f4d\u79fb\u662f20m
\u52192V2+\uff081/2\uff09a\uff082^2\uff09=20
\u5373V1+3a=10\uff0c\u6240\u4ee5\u53ef\u6c42\u51faV1=1m/s\uff0ca=3m/s^2
| 1 m/s 3 m/s 2 绛旓細鍙嶈繃鏉ヨ繍鐢ㄥ叕寮廠=vt+1/2at^2,閫夋嫨绗竴娈典綅绉诲彲浠ヨ绠楀嚭v=1m/s 绛旓細鏍规嵁鍖鍙橀熺洿绾胯繍鍔b鎺ㄨ鈻硏=aT2寰楋細鈻硏=aT2瑙ｅ緱锛歛=6鍙?2鍙ｅ彛锛10m/s2鏍规嵁浣嶇Щ鍏紡寰楋細x1锛漹0t+12at2甯﹀叆鏁版嵁瑙ｅ緱锛歷0=2m/s鎵浠ワ紙t0+2锛塻鏃跺埢b閫熷害涓猴細v=v0+aT=2+2脳10=22m/s绛旓細璐ㄧ偣鍦紙t0+2锛塻鏃跺埢b閫熷害vb澶у皬涓22m/s锛屽姞閫熷害ab澶у皬涓10m/s2 ... 绛旓細绗4绉掑唴鐨勫钩鍧囬熷害鏄14m/s 鍗3.5s鐨勯熷害涓14m/s 鍗砎t=V0+at 鍗14=0+3.5a 鍗砤=4m/sˆ2 绛旓細1. 鍦ㄨ繛缁浉绛夌殑鏃堕棿锛圱锛夊唴鐨勪綅绉讳箣宸负涓鎭掑畾鍊硷紝鍗斥柍s= aT2锛堝張绉鍖鍙橀熺洿绾胯繍鍔ㄧ殑鍒ゅ埆寮忥級鎺ㄨ瘉锛氳鐗╀綋浠ュ垵閫焩0銆佸姞閫熷害a 鍋氬寑鍙橀熺洿绾胯繍鍔紝鑷鏃惰捣鏃堕棿 T鍐呯殑浣嶇Щ鈶犲湪绗2涓猅鍐呯殑浣嶇Щ鈶♀憼鈶′袱寮忓緱杩炵画鐩哥瓑鏃堕棿鍐呬綅绉诲樊涓 鍗宠繘涓姝ユ帹璇佸緱鈥︹2. 鏌愭鏃堕棿鍐呬腑闂存椂鍒荤殑鐬椂閫熷害绛変簬杩欐... 绛旓細2銆佺墿浣撳湪鍓6s鍐呯殑浣嶇Щ涓哄锛歋6 = ½at6² = ½ 脳 6脳6² m = 108 m 3銆 璐ㄧ偣杩愬姩鐨鍔犻熷害澶у皬涓猴細a = 6 m/s²4銆佽璐ㄧ偣缁忚繃12m浣嶇Щ鏃剁殑閫熷害涓篤锛屽垯 V² 锛0 = 2as 鍙緱锛歏 = 鈭2as = 鈭2脳6脳12 m/s = 12 m/s 浠庨珮鑰冭姹傜殑瑙掑害鏉... 绛旓細缁间笂鍙煡锛氱墿浣撳仛鍖鍙橀熺洿绾胯繍鍔ㄦ椂锛屾煇娈典綅绉讳笂涓棿鏃跺埢鐨勯熷害灏忎簬涓棿浣嶇疆鐨勯熷害銆傚嵆 渚1銆涓涓仛鍖鍔犻熺洿绾胯繍鍔ㄧ殑璐ㄧ偣锛鍦ㄨ繛缁浉绛夌殑涓や釜鏃堕棿闂撮殧鍐咃紝閫氳繃鐨勪綅绉诲垎鍒槸24m锛64m锛屾瘡涓涓椂闂撮棿闅斾负4s锛屾眰璐ㄧ偣鐨勫垵閫熷害鍜屽姞閫熷害銆傚垎鏋愶細鍖鍙橀熺洿绾胯繍鍔ㄧ殑瑙勫緥鍙敤澶氫釜鍏紡鎻忚堪锛屽洜鑰岄夋嫨涓嶅悓鐨勫叕寮忥紝鎵瀵瑰簲... 绛旓細璐ㄧ偣鍋氬寑鍔犻熷害鐩寸嚎杩愬姩锛鐢变綅绉诲叕寮忥細s=v 0 t+ 1 2 at 2 寰楋紝灏哠 1 =24 m锛孲 2 =64 m锛孴=2 s鍒嗗埆浠ｅ叆涓婂紡锛屽垪鍑轰袱涓瓑寮忥紝鍗充负s 1 =v 0 T+ 1 2 aT 2 s 2 =v 0 锛圱+2锛+ 1 2 a锛圱+2锛 2 瑙ｅ緱v 0 =7m/s a=7.5m/s 2 ... 绛旓細鍋氬寑鍙橀熺洿绾胯繍鍔ㄧ殑鐗╀綋鍦ㄨ繛缁浉绛夌殑鏃堕棿鍐呴氳繃鐨勪綅绉讳箣宸槸涓涓亽閲忥紝鍗筹細螖x=aT^2 鎵浠ワ細螖x1=BC-AB=aT^2 螖x2=CD-BC=aT^2=螖x1 螖x1+螖x2=(CD-BC)-(BC-AB)=CD-AB=2aT^2 a=(CD-AB)/2T^2=(18m-10m)/[2*(2s)^2]=1m/s^2 ... 绛旓細鍥炵瓟锛鍋氬寑鍙橀熺洿绾胯繍鍔ㄧ殑鐗╀綋鍦ㄨ繛缁浉绛夌殑鏃堕棿鍐呴氳繃鐨勪綅绉讳箣宸槸涓涓亽閲,鍗:螖x=aT^2 鎵浠: 螖x1=BC-AB=aT^2 螖x2=CD-BC=aT^2=螖x1 螖x1+螖x2=(CD-BC)-(BC-AB)=CD-AB=2aT^2 a=(CD-AB)/2T^2=(18m-10m)/[2*(2s)^2]=1m/s^2 绛旓細楂樹腑鐗╃悊鐩寸嚎杩愬姩鐭ヨ瘑鐐1 鍖鍙橀熺洿绾胯繍鍔ㄩ噸瑕佺煡璇嗙偣璁茶В 鍩烘湰姒傚康:鐗╀綋鍦ㄤ竴鏉＄洿绾夸笂杩愬姩,濡傛灉鍦ㄧ浉绛夌殑鏃堕棿鍐呴熷害鐨勫彉鍖栫浉绛,杩欑杩愬姩灏卞彨鍋氬寑鍙橀熺洿绾胯繍鍔銆 涔熷彲瀹氫箟涓:娌跨潃涓鏉＄洿绾,涓斿姞閫熷害涓嶅彉鐨勮繍鍔,鍙仛鍖鍙橀熺洿绾胯繍鍔ㄣ傛部鐫涓鏉＄洿绾,涓斿姞閫熷害鏂瑰悜涓庨熷害鏂瑰悜骞宠鐨勮繍鍔,鍙仛鍖鍙橀熺洿绾胯繍鍔ㄣ 濡傛灉鐗╀綋鐨勯熷害闅... 本站交流只代表网友个人观点，与本站立场无关 |
