A) 11.5 sec
B) 21 sec
C) 5.75 sec
D) 10 sec
Correct Answer: A
Solution :
Here: Initial velocity of stone \[u=0\] Height of the tower \[h=500\text{ }m\] Height of tower is given by, \[h=ut+\frac{1}{2}g{{t}^{2}}\] \[500=0\times t+\frac{1}{2}\times 10{{t}^{2}}\] \[5{{t}^{2}}=500\] or \[t=10\text{ }sec\] (where t is the time taken by the stone to reach water level in lake) The time taken by the sound of splash to reach the point from where the stone is dropped is given by, \[=\frac{height\text{ }of\text{ }tower}{velocity\text{ }of\text{ }sound}\] \[=\frac{500}{330}=1.5\]sec Hence, the sound of splash will be \[=10+1.5=11.5\text{ }sec\]You need to login to perform this action.
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