一铁球从高为80米的塔顶由静止自由下落，求铁球落到塔底须多久（写出详细的计算过程）
\u77f3\u5757A\u81ea\u5854\u9876\u843d\u4e0bm\u7c73\u65f6\uff0c\u77f3\u5757B\u81ea\u79bb\u5854\u9876n\u7c73\u5904\u81ea\u7531\u4e0b\u843d\uff0c\u4e24\u5757\u77f3\u5934\u540c\u65f6\u843d\u5730\uff0c\u5219\u5854\u7684\u9ad8\u5ea6\u4e3a\uff08 \uff09\u8bbe\u5854\u9ad8h\u7c73
A\u4e0b\u843d\u65f6\u95f4\u7531t=\u221a(2h/g\uff09\u77e5\uff1atA=\u221a\uff082h/g)-\u221a(2m/g)
\u540c\u7406\u53ef\u5f97B\u4e0b\u843d\u65f6\u95f4\uff1atB=\u221a\uff082\uff08h-n)/g)
tA=tB,\u5e73\u65b9\u5316\u7b80\u5f97
h=(m+n)^2/4m
\u9898\u76ee\u610f\u601d\u662fA\u81ea\u5854\u9876\u843d\u4e0bS1\u65f6\uff0cB\u4ece\u8ddd\u79bb\u5854\u9876S2\u5904\u5f00\u59cb\u81ea\u7531\u4e0b\u843d\uff0cAB\u540c\u65f6\u843d\u5730\u5427\uff1f
\u5982\u679c\u662f\u8fd9\u6837\u7684\u8bdd\uff0c\u89e3\u7b54\u5982\u4e0b\uff1a
\u8bbe\u5854\u9ad8\u4e3aS\uff0c\u5168\u7a0b\u8017\u65f6t \u6709 t=\u6839\u53f7\uff082S/g\uff09
\u77f3\u5757A\u81ea\u7531\u843d\u4e0bS1\uff0c\u8017\u65f6t1 \u6709 t1=\u6839\u53f7\uff082S1/g\uff09
\u77f3\u5757B\u4ece\u8ddd\u5854\u9876S2\u5904\u81ea\u7531\u4e0b\u843d\u81f3\u5730\u9762\uff0c\u8017\u65f6t2\uff0c \u6709t2=\u6839\u53f7\uff082\uff08S-S2\uff09/g\uff09
\u636e\u9898\u610f\u53ef\u77e5\uff0ct=t1+t2\uff0c\u5373t2=t-t1\u3002\u5c06\u4e0a\u8ff0\u4e09\u65f6\u95f4\u8868\u8fbe\u5f0f\u5e26\u5165\u5373\u53ef\u3002
\u7ed3\u8bba\u4e3a A
\u65b9\u7a0b\u5199\u6210t2=t-t1\uff0c\u662f\u4e3a\u4e86\u4e24\u8fb9\u5e73\u65b9\u6c42\u89e3S\u65f6\u65b9\u4fbf\u4e00\u4e9b
\u6ce8\uff1a\u82e5\u6668\u7ed9\u51fa\u7684\u65b9\u6cd5\u4ea6\u53ef\uff0c\u4f46\u5728\u8ba1\u7b97\u5854\u9ad8\u65f6\uff0cs=vt+1/2gt^2 \u518d\u52a0\u4e0aS1\u662f\u5854\u9ad8\uff0c\u4ee3\u5165\u6570\u636e\u4e4b\u540e\uff0c\u7ed3\u8bba\u662fA\u800c\u4e0d\u662f S1+S2\u3002
\u53ef\u4ee5\u81ea\u884c\u9a8c\u7b97\u4e00\u4e0b
H=1/2at^2
80=1/2×10t^2
t=4s
前提这里的g=10m/s
偶来
绛旓細S=1/2gt鏂 浠ｅ叆80=1/2*10t鏂 寰楀埌t=4绉
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