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P1 Sound and Quakes
Edexcel P1 topic 4 UltraSounds Infrasounds Earthquakes
Question | Answer |
---|---|
What is the frequency range of normal human hearing? | 20 to 20 000Hz |
What are frequencies below 20Hz called? | infrasounds |
What are frequencies above 20 000Hz called? | ultrasounds |
What are infrasounds? | Sounds with a frequency below 20Hz |
What are ultrasounds? | Sounds with a frequency above 20 000Hz |
Which animals use infrasounds? | Big animals like elephants and waves |
What do those animals use infrasounds for? | To communicate |
Name two natural events that emits infrasounds | Meteors and volcanic eruptions |
Which animals use ultrasounds? | Dolphins and bats |
What do those animals use ultrasounds for? | To hunt |
Why would scientists use infrasounds in the jungle? | To locate animals hiding; because you may not SEE the animals but you can record the infrasounds |
Why do we use ultrasounds for foetus? | To see if the foetus is growing properly |
What is the epicentre? | The point of the Earth surface directly above the focus of an Earthquake |
What is the "focus" of an Earthquake? | The point inside the Earth where the Earthquake starts from |
Is a P-wave a longitudinal or a transverse wave? | longitudinal |
Is a S-wave a longitudinal or a transverse wave? | transverse |
Which wave arrives first? S or P? | P |
Why can scientists not predict Earthquakes? | They can not measure the forces between the tectonic plates |
Name 3 uses of ultrasounds. | Sonar (detecting depth of oceans; depth of fish), scanning foetus, communications |
How do you work out the DISTANCE of the echo knowing the TIME of the echo and the SPEED of sound? | Distance = time x speed |
How do you work out the DEPTH of the oceans knowing the DISTANCE of the echo? | Depth = distance echo / 2 |
What makes seismic waves? | An earthquake or an explosion |
What is the instrument that records Earthquakes? | A seismo-meter |
How do scientits work out the location of an Earthquake? | 1)Work out the time difference between when the Pwave and the Swave arrive;2) work out the distance;3) draw a circle of a radius equal to that distance; 4) repeat this for 3 different positions; 5) the epicentre is at the crossing of the 3 circles |
Why is there Earthquakes? | When two tectonic plates slide past each other |
What is the inner core? | Solid Iron |
What is the outer core? | Liquid Iron |
What is the mantle? | Viscous magma |
Why is there convection current inside the mantle? | Radioactive decay inside the core |
What is the crust? | The layer floating on top of the mantle |
What are seismic waves? | Waves caused by an Earthquake |
What is a seismometer? | The instrument used for detecting seismic waves |
State what happens to a P-wave when it crosses from the mantle into the core. | |
The average speed of a P-wave in the mantle is 12 km/s. A P-wave travels vertically down from the surface to boundary core-mantle and reflects back to the surface. It travels a total distance of 5800 km. Calculate the total time of travel for the wave. | |
Explain the difference between transverse and longitudinal waves by referring to sound from a bell and the light from a lamp. |