? 發問時間: 科學其他:科學 · 2 0 年前

物理, 關於位移

1. A ball is thrown downward (not dropped) from the top of a tower. After being released, its downward acceleration will be

a. greater than g.

b. exactly g.

c. smaller than g.

d. need more information

2 . Is it possible for an object\'s instantaneous velocity and instantaneous acceleration to be of opposite sign at some instant of time?

a. yes

b. no

c. need more information

3 . The slope of the curve in the position vs. time graph for a particle\'s motion gives:

a. the particle\'s speed

b. the particle\'s acceleration

c. the particle\'s average velocity

d. the particle\'s instantaneous velocity

e. not covered in the reading assignment

2 個解答

評分
  • 2 0 年前
    最佳解答

    1.b. exactly g.   不管用丟的還是自由落下  自由落體的加速度就是g2.a. yes   順時速度和順時加速度有可能是反向的3^^.第三題不太懂 Sorry

  • 2 0 年前

    1,2題同上

    第三題:

    X-t圖中 物體運動軌跡的切線斜率代表物體的 "瞬時速度"

    因為 dx/dt=v(即在趨近於零的時間內 ,物體位移除以時間等於"瞬時速度")

    答案選 (d)

    參考資料: 自己
還有問題?馬上發問,尋求解答。