A) 2s
B) 5 s
C) 7s
D) 9 s
Correct Answer: C
Solution :
Vertical component of initial velocity \[=50\sin {{30}^{o}}\]\[=25\,m/s.\] \[U\sin \,g\,s=ut+\frac{1}{2}a{{t}^{2}}\]along the y-axis \[-70=25t-\frac{1}{2}\times 10\times {{t}^{2}}\] or \[5{{t}^{2}}-25t-70=0\] or \[{{t}^{2}}-5t-14=0\] or \[t(t-7)+2(t-7)=0\] or \[t=7\,\sec .\] Hence, the correction option is [c].You need to login to perform this action.
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