The table displays the velocity of sound in various materials.
Substance:
Air
Water
Rock
Speed (meters per second):
344
1,437
3,000
Based on the data presented in the table, which of the following boys would be able to hear a rock falling off a cliff one kilometer away?
A boy lying down with his ear to the ground
A boy sitting in a tree with his ear to the bark
A boy sitting on the grass
A boy swimming in the water
Based on the data presented in the table, the velocity of sound in air is 344 meters per second, in water it is 1,437 meters per second, and in rock it is 3,000 meters per second.
To determine which boy would be able to hear a rock falling off a cliff one kilometer away, we need to consider the medium through which sound travels.
1. A boy lying down with his ear to the ground: This boy would be closest to the rock by having his ear to the ground, which is in direct contact with the rock (assuming the cliff is made of rock). Since the speed of sound in rock is 3,000 meters per second, he should be able to hear the rock falling off the cliff.
2. A boy sitting in a tree with his ear to the bark: Although the boy is elevated in a tree, his ear is in contact with the bark, which is not a good conductor of sound. Additionally, the speed of sound in wood is not provided, so we cannot determine if he would be able to hear the rock falling off the cliff.
3. A boy sitting on the grass: The boy sitting on the grass is in contact with the air, and the speed of sound in air is 344 meters per second. Given that the rock is a kilometer away, it would take approximately (1000 / 344) seconds for the sound to reach the boy. This means there would be a significant delay, and he might not be able to hear the rock falling off the cliff.
4. A boy swimming in the water: The boy swimming in the water is in direct contact with the water, which is a better conductor of sound than air. However, the speed of sound in water is 1,437 meters per second, which is slower than the speed of sound in rock. Therefore, he would not be able to hear the rock falling off the cliff.
Based on the given options, the boy lying down with his ear to the ground would be most likely to hear the rock falling off a cliff one kilometer away.