A) 2 s
B) 5 s
C) 7 s
D) 9 s
E) None of these
Correct Answer: C
Solution :
The vertical component of velocity of projection\[~=-\,50\text{ sin}\,30{}^\circ \] \[=-25\text{ }m\text{/}s\] If \[t\] be the time taken to reach the ground \[\therefore \] \[h=ut+\frac{1}{2}g{{t}^{2}}\] \[70=-\,25\,t+\frac{1}{2}\times 10\times {{t}^{2}}\] \[70=-\,25\,t+5\,{{t}^{2}}\] \[{{t}^{2}}-5t-14=0\] \[t=-\,2s\]and \[7\,s\] Since \[t=-\,2\,s\] is not valid so \[t=7\,s\]You need to login to perform this action.
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