question_answer

A stuntman plans to run across a rooftop and then horizontally off it to land on the roof of the next building. The roof of the next building is 4.9 m below the first one and 6.2 m away from it. What should be his minimum speed, in m/s, so that he can successfully make the jump

A)  3.1               

B)  4.1

C)  4.9              

D)  6.2,

Correct Answer: D

Solution :

: Vertical height = 4.9 m \[\therefore \] \[h=ut+\frac{1}{2}g{{t}^{2}}\] or \[4.9=0+\frac{1}{2}\times 9.8{{t}^{2}}\]or\[4.9{{t}^{2}}=4.9\] or \[{{t}^{2}}=1\]             or \[t=1\text{ }sec\] Horizontal velocity \[=v\] \[\therefore \] Range= 6.2 m;   \[\therefore \] \[v\times time=6.2\] or \[v\times 1=6.2\]        or \[v=6.2\text{ }m/s\]