A man throws a stone horizontally off an 80m cliff. How fast must the stone
travel so that it leaves the cliff top to land on ground which is 100m far from
the base of the cliff?
physics problem about motion
2010-04-06 1:12 am
回答 (1)
2010-04-06 1:26 am
✔ 最佳答案
Let V be the required velocity of the stone.Time required to travel 100m horizontally = 100/V
Consider the vertical motion, use equation of motion: s = ut + (1/2)a.t^2, with u = 0 m/s, a = -g(=-10 m/s2), s = -80 m, t = ?
hence, -80 = (1/2)(-10).t^2
t = 4 s
Therefore, 100/V = 4
i.e. V = 100/4 m/s = 25 m/s
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