If a water wave oscillates up and down 5 times in 25 seconds and the distance between wave crests is 15 meters. What is the wave speed?

Question

If a water wave oscillates up and down 5 times in 25 seconds and the distance between wave crests is 15 meters. What is the wave speed?

Answer 1

If a wave occurs 5 times in 25 seconds, you know the frequecy, 5 cycles in 25 seconds = 5 Hz or 5 cycles per second.

If the distance between the crests is 15m, you know the wavelength, since wavelength is the distance between two identical points on adjacent waves.

 

 Since wave speed is frequency x wavelength   v = f x λ = 5 x 15 = 75m/s

 

Answer 2

For wave speed, we want to use the following formula:

v = f • λ

v=speed
f= frequency
λ=wavelength

Plug in your values, simplify, and solve.

v= (5 cycles/25s) • 15m
v=.2Hz • 15m
v= 3m/s

Here's a great website for more information about the wave equation!
http://www.physicsclassroom.com/class/waves/Lesson-2/The-Wave-Equation