Two small boat are `10 m` apart on a lake. Each pops up and down with a period of `4.0` seconds due to wave motion on the surface of water. When one boat is at its highest point, the other boat is at its lowest point. Both boats are always within a single cycle of the waves. The speed of the waves is :

Options

A. 2m/sec
B. 2.5 m/s
C. 10 m/s
D. 5 m/sec

Answer

D

Explanation

distance between crest and trough `=(lambda)/2=10 m`
`rArr lambda=20 m`
time period T=4sec
`:. V=lambda//T =20 m //4 sec`
=5 m/s