Waves equation problems

Question

1.A person yells across a canyon and hears the echo 9.7 seconds later. If the speed of sound is 344.9 m/s, how far away is the other side of the canyon?

2.Radio station WKLB in Boston broadcasts at a frequency of 90.7 kHz. What is the wavelength of the radio waves emitted by WKLB? ( Radio waves travel at the speed of light 3x10⁸ m/s) ps. no decimals

3.Water waves at a lake cross a distance of 6 m in 2.4 s. The period of oscillation is 5 s. What is the speed of the water waves?

*answer and explanation please*

Answer 1

I hope this is helpful!

Answer 2

1.A person yells across a canyon and hears the echo 9.7 seconds later. If the speed of sound is 344.9 m/s, how far away is the other side of the canyon?

Distance = speed x time; distance = 344.9*9.7 = 3345.53m

This is the total distance travelled by the sound in going and then returning so the canyon wall is half that distance away.

2.Radio station WKLB in Boston broadcasts at a frequency of 90.7 kHz. What is the wavelength of the radio waves emitted by WKLB? ( Radio waves travel at the speed of light 3x10⁸ m/s) ps. no decimals

wave equation is v = ƒ•λ

or 3x10⁸ = 90.7•1000Hz•λ

therefore the wavelength (λ) = 3x10⁸/(90.7•1000) = 3308m

3.Water waves at a lake cross a distance of 6 m in 2.4 s. The period of oscillation is 5 s. What is the speed of the water waves?



If the waves travel 6m in 2.4s then v = d/t, = 6/2.4 = 2.5m/s. the period of oscillation is superfluous on this question.