A) \[6\text{ }m{{s}^{-1}}\]
B) \[8\text{ }m{{s}^{-1}}\]
C) \[10\text{ }m{{s}^{-1}}\]
D) \[14\text{ }m{{s}^{-1}}\]
Correct Answer: C
Solution :
Given, \[y=8t-5{{t}^{2}}\] ...(i) \[x=6t\] ...(ii) We know, \[x=(u\,cos\theta )t\] ...(iii) Compare with Eq. (ii), we get \[{{u}_{1}}\,cos\theta =\frac{x}{t}=6\] and \[y=(u\sin \theta )t-\frac{1}{2}g{{t}^{2}}\] compare with Eq (i), we get \[{{u}_{2}}\sin \theta =8\] \[\therefore \] \[u=\sqrt{u_{1}^{2}+u_{2}^{2}}\] \[u=\sqrt{36+64}\] \[u=10\,m{{s}^{-1}}\]You need to login to perform this action.
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