哈利波特 發問時間: 科學其他:科學 · 1 0 年前

物理好難 我不會 救救我

A railroad car for mass 2.50× 10的4次方kg is moving with a speed of 4.00m/s.It collides and couples with three other coupled railroad cars,each of the same mass as the single car ang moving in the same direction with an initial speed of 2.00 m\s,(a)what is speed of the four cars imme-diately after the collision?(b)How much enegert is trans-formed into internal enegy in the collision?

1 個解答

評分
  • 1 0 年前
    最佳解答

    (a).

    令碰撞後速度為v3,則:

    m1v1+m2v2=(m1+m2)v3

    =>m1*4+3*m1*2=4*m1*v3

    =>m1*10=4*m1*v3

    =>v3=2.5 m/s

    (b)

    Eloss=(1/2)(m1)(v1^2)+(1/2)(m2)(v2^2)-(1/2)(m1+m2)(v3^2)

    =(1/2)(m1)(16)+(1/2)(3m1)(4)-(1/2)(4m1)(6.25)

    =0.5*2.5*10^4*(16+12-25)=37500 J.

還有問題?馬上發問,尋求解答。