2. (a) Earthquakes produce seismic waves and infrasound waves - Edexcel - GCSE Physics - Question 2 - 2012 - Paper 1
Question 2
2. (a) Earthquakes produce seismic waves and infrasound waves.
Which row of the table is correct for these waves?
Put a cross (✔) in a box to show your answer.
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Worked Solution & Example Answer:2. (a) Earthquakes produce seismic waves and infrasound waves - Edexcel - GCSE Physics - Question 2 - 2012 - Paper 1
Step 1
(a) Which row of the table is correct for these waves?
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Answer
The correct answer is A. Seismic waves are longitudinal only, while infrasound waves are longitudinal and transverse.
Step 2
(b)(i) State what happens to a P-wave when it crosses from the mantle into the core.
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Answer
When a P-wave crosses from the mantle into the core, it slows down significantly and its propagation may also change due to the differing material properties.
Step 3
(b)(ii) Describe how the speed of a P-wave changes between a depth of 1000 km and 2500 km.
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Answer
Between a depth of 1000 km and 2500 km, the speed of a P-wave generally increases due to the increasing density and pressure of the material.
Step 4
(b)(iii) Calculate the total time of travel for the wave.
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Answer
To find the total time of travel, we first calculate the time taken to travel down and then back up. The total distance traveled is 5800 km, and since the average speed in the mantle is 12 km/s, we can calculate:
Total travel time = Total distance / Average speed
Total travel time = 5800 km / 12 km/s = 483.33 seconds.
Step 5
(c) Explain what the results show about predicting earthquakes.
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Answer
The results indicate that predicting earthquakes is difficult. This is because there is no consistent pattern to the forces needed to start the block moving; the values vary significantly among students. This inconsistency reflects the unpredictability of the forces acting on tectonic plates.
