A paper boat vibrating on small waves made 5 vibrations in 10 s

A paper boat vibrating on small waves made 5 vibrations in 10 s. What was the speed of the waves if the distance between their adjacent crests was 20 cm?

Given:

t = 10 seconds – time interval;

n = 5 oscillations – the number of oscillations that the boat made during the time interval t;

l = 20 centimeters – the distance between two adjacent wave crests (wavelength).

It is required to determine u (meter / second) – the speed of wave propagation.

We translate the units of measurement of length into the SI system:

l = 20 cm = 20 * 10-2 = 20/100 = 0.2 meters.

Let’s find the period of the wave oscillation:

T = t / n = 10/5 = 2 seconds.

Then the wave propagation speed will be equal to:

u = l / T = 0.2 / 2 = 0.1 m / s.

Answer: the wave propagation speed is 0.1 m / s.