How long will it take for the echo to return

[rrosa522]

Homework Statement

A submarine sends out a sonar wave that has
a frequency of 545 Hz. If the wavelength of the
sound is 2.60 m, how long does it take for the
echo to return when the sound is reflected from
a submarine that is 5.50 km away?

Homework Equations

The Attempt at a Solution

i used the equation p=1/f and i plugged in frequency and got 0.00183 seconds, the right answer should be around 7-8 seconds

 

[SteamKing]

Homework Statement

A submarine sends out a sonar wave that has
a frequency of 545 Hz. If the wavelength of the
sound is 2.60 m, how long does it take for the
echo to return when the sound is reflected from
a submarine that is 5.50 km away?

Homework Equations

The Attempt at a Solution

i used the equation p=1/f and i plugged in frequency and got 0.00183 seconds, the right answer should be around 7-8 seconds

Well let's see here. Is it perhaps you calculated the period of one wavelength and overlooked the fact that it takes more than one wave of length 2.60 m to cover the distance of 5.50 km to the object and then 5.50 km back again to the sub?

 

[rrosa522]

Well let's see here. Is it perhaps you calculated the period of one wavelength and overlooked the fact that it takes more than one wave of length 2.60 m to cover the distance of 5.50 km to the object and then 5.50 km back again to the sub?

thank you so much, i finally got the right answer!