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A man uses a dog whistle to call his dog - Edexcel - GCSE Physics - Question 4 - 2014 - Paper 1
Question 4
A man uses a dog whistle to call his dog. The whistle uses ultrasound. (i) The dog can hear the whistle but the man cannot. Explain why the dog can hear the whist... show full transcript
Worked Solution & Example Answer:A man uses a dog whistle to call his dog - Edexcel - GCSE Physics - Question 4 - 2014 - Paper 1
Step 1
Explain why the dog can hear the whistle but the man cannot.
Answer
The dog can hear the whistle because it produces sound at a frequency above 20,000 Hz, which falls within the range of ultrasound. Humans cannot hear sounds above this frequency, as their hearing range typically caps at around 20,000 Hz.
Step 2
Calculate the speed of ultrasound.
Answer
To calculate the speed of ultrasound, we can use the formula:
v = \frac{d}{t}$$ where: - $d$ is the distance (140 m) - $t$ is the time (0.42 s) Substituting the values:v = \frac{140 , \text{m}}{0.42 , \text{s}} = 333.33 , \text{m/s}$$
Therefore, the speed of ultrasound is approximately 330 m/s.
Step 3
Complete the sentence by putting a cross (X) in the box next to your answer.
Answer
The earthquake P-wave is
☒ A. an infrasound wave ☒ B. an ultrasound wave ☒ C. an electromagnetic wave ☑ D. a transverse wave
Since earthquake P-waves are classified as primary waves, they are longitudinal waves and do not fit the category of transverse waves.