Question

A boat at anchor is rocked by waves whose crests are 100 m a part and whose velocity is $$25 \mathrm{~ms}^{-1}$$. These waves reach the boat every ______.

Options

• 2,500 s

• 75 s

• 4 s

• 0.25 s

Answer 1

A boat at anchor is rocked by waves whose crests are 100 m a part and whose velocity is $$25 \mathrm{~ms}^{-1}$$. These waves reach the boat every 4 s.

Explanation:

Given: \[ \lambda=100\ \text{m}\]

\[v=25\ \text{m s}^{-1} \]

Time between successive crests is the time period:

\[ T=\frac{\lambda}{v} \]

\[ =\frac{100}{25}\]

= 4 s