question_answer

A boat at anchor is rocked by waves whose crests are 50m apart. If the crests are moving at\[\text{2}0\text{m}{{\text{s}}^{-\text{1}}}\], how often do they reach the boat?

Answer:

Given \[\lambda =50m\]  \[v=20m/s\] \[T=?\] Now      \[T=\lambda /v\]                                 \[=50/20\]                                 \[=2.5s.\]