Answer:
\[u=34.3\,m/s\] \[h=147\,\,m\] \[g=9.8m/{{s}^{2}}\] \[t=?\]
For a body projected up from the top of the tower, \[h=-ut+\frac{1}{2}a{{t}^{2}}\] \[\Rightarrow 147=-34.t+4.9\,\,{{t}^{2}}\] \[(or)\,\,4.9\,{{t}^{2}}-34.3t\,-147=0\] \[i.e.\,\,{{t}^{2}}-7t-30=0\] \[i.e.\,\,(t-10)(t+3)=0\] \[i.e.\,\,t=10s\]
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