Q2DQ - University Physics with Modern Physics

Question

The hero of a western movie listens for an oncoming train by putting his ear to the track. Why does this method give an earlier warning of the approach of a train than just listening in the usual way?

Step-by-Step Solution

Answer

The speed of the sound is more in metal so the warning is obtained earlier than the air medium.

Step 1: Write the given data:

The person keeps the ear on the track to determine the an oncoming train.

Step 2: Determine the concept

Consider the relation between the wavelength and the frequency of the wave as:

$\mathit{\lambda }\mathbf{=}\frac{{\mathbf{v}}_{\mathbf{s}}}{\mathbf{f}}$

Step 3: Determine the explanation for the given question

Consider the speed of the wave depend on the properties of the material and is the product of the wavelength and the frequency of the wave. Since, water and air have different properties so the speed of the wave will change.

Consider the speed of the sound is more in the metals like in steel, if the ear is kept on track the warning sign is obtained that the train is approaching fast.

Therefore, the speed of the sound is more in metal so the warning is obtained earlier than the air medium.