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. A boy lying down with his ear to the ground
B. A boy sitting in a tree with his ear to the bark
C. A boy sitting on the grass
D. A boy swimming in the water
Based on the data presented in the table, the speed of sound in rock is given as 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 most easily and quickly.
The speed of sound in air is given as 344 meters per second, which means that sound travels slower in air compared to rock.
Similarly, the speed of sound in water is given as 1,437 meters per second, which means that sound travels slower in water compared to rock.
Therefore, the answer is not A or D because the speed of sound in air or water is slower than in rock.
When sound travels from one medium to another, it can change direction and speed. This is called refraction. Since sound will refract upon entering a different medium, it is unlikely that the sound of the rock falling off a cliff would be able to travel through the air or water and be heard by the boys in options A or D.
Hence, the most suitable option is B. A boy sitting in a tree with his ear to the bark. The speed of sound in rock is closest to the speed of sound in rock itself, so this boy would be the most likely to hear the rock falling off a cliff one kilometer away.