Anonymous
Anonymous asked in 科學其他:科學 · 2 decades ago

Two 2.0kg bodies,A and B......

Two 2.0kg bodies,A and B collide. The velocities vefore the collison are VA=(15i 30j)

m/s and VB=(-10i 5.0j)m/s. After the collision, VA'=(-5.0i 20j)m/s. What are (a)the final velocity of B and (b)the change in the total kinetic energy(including sign)?

Update:

VA,VB,i,j為向量.

2 Answers

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  • Favorite Answer

    不管啥碰撞,動量都會守恆

    所以此題用動量守恆解就行了

    2005-12-18 22:39:21 補充:

    水平(X方向)動量守恆:

    2*15+2*(-10)=2*(-5)+2*(Vx),得Vx=10

    垂直(Y方向)動量守恆:

    2*30+2*5=2*20+2*(Vy),得Vy=15

    故VB=10i+15j

    總動能改變量=後動能-前動能

    =(1/2)*(2)*(10^2+15^2)+(1/2)*(2)*(5^2+20^2)

    -(1/2)*(2)*(10^2+5^2)-(1/2)*(2)*(15^2+30^2)

    =325+425-125-1125

    =-500J

  • 2 decades ago

    這個問題要看什麼樣的碰撞吧!完全彈性碰撞,非彈性碰撞,還是完全非彈性碰撞?

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