精品偷拍一区二区三区,亚洲精品永久 码,亚洲综合日韩精品欧美国产,亚洲国产日韩a在线亚洲

  • <center id="usuqs"></center>
  • 
    
  • 某物體由A點(diǎn)靜止開(kāi)始做勻加速直線運(yùn)動(dòng),加速度大小為a1,經(jīng)時(shí)間t后到達(dá)B點(diǎn),隨即使物體的加速度大小變?yōu)閍2,方向與a1相反,再經(jīng)時(shí)間t物體回到A點(diǎn).求:

    某物體由A點(diǎn)靜止開(kāi)始做勻加速直線運(yùn)動(dòng),加速度大小為a1,經(jīng)時(shí)間t后到達(dá)B點(diǎn),隨即使物體的加速度大小變?yōu)閍2,方向與a1相反,再經(jīng)時(shí)間t物體回到A點(diǎn).求:
    (1)物體在B點(diǎn)和回到A點(diǎn)時(shí)的速率之比.
    (2)加速度a1和a2的大小之比.
    物理人氣:267 ℃時(shí)間:2019-08-19 08:27:47
    優(yōu)質(zhì)解答
    物體從A點(diǎn)到達(dá)B點(diǎn)的速度為:Vb=a1t,物體從B點(diǎn)回到A點(diǎn)的速度為:Va=a1t-a2t
    則有:Vb:Va=a1t:(a1t-a2t)=a1:(a1-a2)當(dāng)物體速度由a1t變?yōu)?。t1=a1t/a2,物體速度由0返回到B點(diǎn)時(shí):t2=t1=a1t/a2,再由B點(diǎn)返回到A點(diǎn)時(shí)有:Va^2-Vb^2=2a2a1t^2由:Vb:Va=a1:(a1-a2)則:[(a1-a2)Vb/a1]^2+Vb^2=2a2a1t^2,Vb=a1t[(a1-a2)t]^2+(a1t)^2=2a2a1t^2(a1-a2)^2+a1^2=2a2a1整理的:2a1^2-4a1a2+a2^2=0解得:a1=(4a2±a2√8)/4由題可得:a1=(4a2-a2√8)/4 為真解。得:a1:a2=(2-√2):2再由B點(diǎn)返回到A點(diǎn)時(shí)有:Va^2-Vb^2=2a2a1t^2由:Vb:Va=a1:(a1-a2)則:[(a1-a2)Vb/a1]^2+Vb^2=a2a1t^2,Vb=a1t[(a1-a2)t]^2+(a1t)^2=a2a1t^2(a1-a2)^2+a1^2=a2a1整理的:(a1-a2)^2+a1(a1-a2)=0則有:(a1-a2)(2a1-a2)=0a1=a2,a1=a2/2由題可得:a1=a2/2 為真解。得:a1:a2=1:2Va^2-Vb^2=2a2a1t^2應(yīng)該為:Va^2-Vb^2=a2a1t^22、當(dāng)物體速度由a1t變?yōu)?。t1=a1t/a2,物體速度由0返回到B點(diǎn)時(shí):t2=t1=a1t/a2,再由B點(diǎn)返回到A點(diǎn)時(shí)有:Vb(t-2t1)+a2(t-2t1)^2/2=a1t^2/2,Vb=a1t,t1=a1t/a2則有:2a1t(t-2a1t/a2)+a2(t-2a1t/a2)^2=a1t^2整理:2a1(1-2a1/a2)+a2(1-2a1/a2)^2=a1 2a1(a2-2a1)+(a2-2a1)^2=a1a22a1a2-4a1^2+a2^2-4a1a2+4a1^2=a1a2 a2^2-2a1a2=a1a2 a2^2-3a1a2=0a2(a2-3a1)=0 則有:a2=3a1,故:a1:a2=1:3
    我來(lái)回答
    類似推薦
    請(qǐng)使用1024x768 IE6.0或更高版本瀏覽器瀏覽本站點(diǎn),以保證最佳閱讀效果。本頁(yè)提供作業(yè)小助手,一起搜作業(yè)以及作業(yè)好幫手最新版!
    版權(quán)所有 CopyRight © 2012-2024 作業(yè)小助手 All Rights Reserved. 手機(jī)版