The sound of distant horses can be heard by applying the ear to the ground whereas it is inaudible if the ear is held a little distance above the ground. Explain.

Explanation

We know that loudness is directly proportional to the density of the medium. The density of ground is much higher than that of air. Thus, the sound of distant horses, when conveyed through ground, is louder then when through air. Therefore, by applying ear to the ground, we can hear this sound. But when the ear is a little distance above the ground, the sound travels though air and is hardly audible. A part from it, velocity of sound in solid (like ground) is more so ground facilitates transfer of sound energy with greater intensity.