Question

A boat is rocked by waves of velocity $25 \,m/s$ having crests $100\, m$ apart. They reach the boat once every

• A. 4.0 s
• B. 8.0 s
• C. 2.0 s
• D. 0.25 s

Answer 1

Answer: (A)

4.0 s

Answer 2

The required relation can be given as $v=n\lambda$ Given, $v=25\,m/s,\,\lambda =100\,m$ $\therefore$ $25=n\times 100$ $\Rightarrow$ $n=\frac{25}{100}=\frac{1}{4}$ $\Rightarrow n = 0.25$ Then, $T=\frac{1}{n}=\frac{1}{0.25}=4\,s$