本题目来源于试卷: Space Time & Motion A.3 Work Energy and Power，类别为 IB物理学
[单选题]
A lead ball is droppeslg) o*8x ls .qd:(o7wiujx. bdbjs +n.0)h mxa from a height of $12\;m$ above the ground. Assuming that air resistance is negligible, which of the following expressions best describes the total energy of the ball when it is at a height of $3\;m$ above the ground in terms of its kinetic energy ($E_k$) and gravitational potential energy ($E_p$)?
A. $E_k - E_p$
B. $E_k + E_p$
C. $E_k$ only
D. $E_p$ only
参考答案: B
本题详细解析:
Explanation: The total energy at any given instant is the sum of $E_k$ and $E_p$
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