Ultrasound waves are sound waves which have a frequency higher than the upper limit for human hearing - above 20,000 Hz.
Ultrasound waves are longitudinal because they are simply high frequency sound waves i.e. above 20 kHz.
Different species of animal have different hearing ranges.
This explains why a dog can hear the ultrasound produced by a dog whistle, but humans cannot.
A builder uses an ultrasonic device to measure the length of a room.
The device shows that the distance from one wall to the opposite wall is 8.25 m.
If the speed of ultrasound in air is 330 m/s, how long does it take for the ultrasound to travel to the far wall and back again?
Distance to opposite wall = 8.25 m
Speed of sound = 330 m/s
Time taken from device to opposite wall =
Time taken from device to opposite wall = 0.025 s
Time taken from device to opposite wall and back again:
= 0.025 s x 2 = 0.050 s
The time taken for the ultrasound to travel to the far wall and back again is 0.050 s.