For long range communication an elephant uses a low frequency rumble that is undetectable to human ears. One elephant can pick up another elephant's call from a distance of 10 km. The frequency of this rumble is about 13 Hz. How fast does the rumble travel?

my teacher said the answer is 769.2 m/s im confused and have a test tomorrow.:(

The rumble is a sound, and sound travels at a speed of 343 m/s in air.

The answer that was given is more than twice the speed of sound. Since we already know the speed of sound, we can
only calculate the time required to travel 10km.

VT = 10,000 m
343T = 10,000

To calculate the speed at which the rumble travels, we can use the formula:

Speed = Wavelength × Frequency

First, let's find the wavelength of the rumble. The wavelength is the distance between two consecutive peaks or troughs of a wave. We can use the formula:

Wavelength = Speed of Light / Frequency

The speed of light in a vacuum is approximately 3 × 10^8 m/s. However, for sound waves in air, the speed is slightly different. Typically, the speed of sound in air at room temperature is about 343 m/s.

So, let's use the speed of sound in air (343 m/s) to calculate the wavelength:

Wavelength = (Speed of Sound) / Frequency
Wavelength = 343 m/s / 13 Hz
Wavelength ≈ 26.38 m

Now that we have the wavelength, we can calculate the speed of the rumble:

Speed = Wavelength × Frequency
Speed ≈ 26.38 m × 13 Hz
Speed ≈ 342.94 m/s

Therefore, the speed at which the rumble travels is approximately 342.94 m/s. It seems that your teacher made a mistake in their calculation, and the correct answer is not 769.2 m/s.