To navigate, a porpoise emits a sound wave that has a wavelength of 4.9 cm. the speed at which the wave travels in seawater is 1522 m/s. find the period of the wave.

Frequency can be defined as the ratio between the speed of the wave and its wavelength, that is

At the same time, the frequency is the inverse of the Period so

If we join the two expressions we will have to

Replacing we have that

Therefore the period of the wave is

e) none of the above answers are correct

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day