A) 9 s and 1800 m
B) 8 s and 1500 m
C) 3 s and 2000 m
D) 5 s and 500 m
Correct Answer: A
Solution :
Firstly convert the unit of velcotiy in metre per second, because velocity is given in km/h and height in metre. Horizontal velocity =720 km/h \[=720\times \frac{5}{18}\] \[=200\,m/s\] Vertical height of plane = 396.9 m \[h=ut+\frac{1}{2}g{{t}^{2}}\] Since, \[u=0,\]so \[396.9=\frac{1}{2}\times 9.8\times {{t}^{2}}\] \[\Rightarrow \] \[{{t}^{2}}=81\] \[\Rightarrow \] \[t=9s\] Horizontal range = horizontal velocity \[\times \] time \[=200\times 9\] = 1800 mYou need to login to perform this action.
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