P1 topic 4 edexcel

Pregunta	Respuesta
Define infrasound	Sound with lower frequencies than 20Hz.
Define ultrasound	Sound with a frequency greater than 20000Hz
Give four uses of infrasound	Communication between animals, detects animal movement in remote areas, detection of volcanic eruptions and meteors.
Give three uses of ultrasound	Sonar, communication between animals, foetal scanning.
A ship detects a sonar pulse 3 seconds after it was emitted. The speed of sound in water is 1500m/s. Calculate the depth of the water and the distance the wave has travelled.	Answers: depth - 2250m distance travelled - 4500m
What two events cause seismic waves?	Earthquakes and explosions
Seismic waves can be S or P waves. What type of wave are each of these?	S – transverse, P – longitudinal.
What two things can happen to a seismic wave at boundaries between the crust, mantle or core?	Reflected or refracted.
What is the outermost layer of the earth composed of and what do these do?	Tectonic plates, move due to convection currents in the mantle.
What natural event can happen at a plate boundary and what is released?	Plates sliding past each other releasing energy

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