Question

A stone is dropped into a lake from a tower $500 \,m$ high. The sound of the splash will be heard by a man on the tower after: [Assume speed of sound $\left.=330\, m / s ; g =10 \,m / s ^{2}\right]$

• A. 10 s
• B. 11.5 s
• C. 14 s
• D. 21 s

Answer 1

Answer: (B)

11.5 s

Answer 2

As $\frac{1}{2}gt^2$ = $\therefore$ t = $\sqrt{\frac{2S}{g}} = \sqrt{\frac{2 \times 500}{10}}$ = 10 s Time taken by sound = $\frac{500}{350}$ = 1.5 s Total time = 10 + 1.5 = 11.5 s