P1.4 Flashcards
1
Q
What are p-waves?
A
They are longitudinal seismic waves that travel through the earth
2
Q
What are s-waves?
A
They are transverse seismic waves that travel through the earth
3
Q
What are infrasound waves?
A
- they have sound frequencies less than 20hz
- used for communication between animals
- used to detect animal movement in remote locations
- used to detect volcanic eruptions and meteors
4
Q
What are ultrasound waves?
A
- they have sound frequencies greater than 20,000hz
- used in sonar
- used in communication between animals
- used in foetal scanning
- used to calculate the depth of the sea
5
Q
What are frequencies?
A
The number if cycles of a wave per second, measured in hertz
6
Q
What is the epicentre?
A
It’s the point on the surface of the earth directly above the focus of an earthquake
7
Q
What is sonar?
A
Sonar is a technique used by ships to determine the depth of water.
8
Q
How does sonar work?
A
- Pulses of ultrasound are reflected off the bottom of the seabed
- The time delay between sending the pulse and receiving the echo is used to calculate the distance travelled
9
Q
How to work out distance travelled by ultrasound pulse?
A
speed of ultrasound X time delay
