✔ 最佳答案
假設係地球上面發生, 而個gravitational field is constant, 咁兩個同樣的波係同一時間一齊放手 (release from rest), 如果再neglect 埋air resistance effect, 咁樣理論上係會係同樣時間著地的.
因為佢地之間只係關係到kinematics , 即係 v = u+at; v^2-u^2=2as; s=ut +1/2at^2 等等.....
就今次來講呢, 我地可以用v = u+at 同 v^2-u^2=2as 來解釋.
因為大家都係release from rest, 所以大家的u 也是0, 用第一條式(v = u+at),
==> v = at
==>咁因為大家的時間都係一樣, 而個acceleration 都係一樣,
==> 所以佢地個v 都會係一樣
再用第二條式(v^2-u^2=2as)
==> u=0, v and a is the same,
==>所以s 都會係一樣
==> 咁即係話佢地的displacement travel 係一樣, 但係現在其中一個波早d 到地下
==> 由呢一樣野就可以deduce 到 兩個波的inital height 係唔一樣
==> 所以兩個波的inital potential energy 都唔同啦
我講咁多野都係想你知道點解, 而唔係只係記得個答案. 始終 Method 緊要過 answer 好多啦.
2007-03-13 12:45:26 補充：
又有另一個答法會簡單d. 就係諗吓個total energy. BALL A 係撞地時velocity 大過 BALL B (即係同一高度的時候, ball A 的 kinetic energy 大過 ball B)== that means the totally energy on Ball A is larger== therefore, if all the energy is stored as potential energy== ball A mush higher than ball B since U = mgh
