Question

According to the information in the table, which of the following boys would hear a rock fall off of a cliff a kilometer away?

a boy lying down with his ear to the ground
a boy sitting on the grass
a boy sitting in a tree with his ear to the bark
a boy swimming in the water

Answer 1

The boy lying down with his ear to the ground and the boy sitting in a tree with his ear to the bark.

Reason: solids (ground, tree wood) transmit sound and vibrations much better than air, so they would pick up the distant fall. Sitting on the grass (air) or swimming (liquid surface coupling is poor) would be much less likely to hear it from 1 km.