9TH GRADE PRACTICE
Physics Problems: Mechanical waves and sound, Grade 9
Types of waves, length, speed, properties and perception of sound.
Here the conditions and analysis of the solution can be read without an account. In the simulator, you need to collect the same analyzes yourself: “Given,” formulas, order of steps and answer.
Problem statements
The answer options are there to check against, and the walkthrough opens under each problem.
Problem #34
Mechanical wavesEvaluate the statement: In a longitudinal wave, particles oscillate along the propagation, and in a transverse wave, particles oscillate perpendicular to it.
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The sound in a gas is longitudinal, and the wave on a stretched string is transverse in a simple way.
Answer
Problem #35
Mechanical wavesEvaluate the statement: the concept “Mechanical wave” means: The distance between the nearest points that oscillate equally is equal to the path of the wave in one period.
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Particles of the medium oscillate around equilibrium, transmitting disturbance to their neighbors.
Answer
Problem #36
Mechanical wavesThe wave travels at a speed of 340 m/s and has a frequency of 170 Hz. Find the wavelength.
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Answer
Problem #37
Sound, echo and resonanceEvaluate the statement: Pitch is primarily related to frequency, loudness is related to intensity, and timbre is related to the spectral composition of sound.
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The same note of different instruments differs in timbre due to different sets of overtones.
Answer
Problem #38
Sound, echo and resonanceEvaluate the statement: The concept “Infrasound and ultrasound” means: An echo is a sound that returns after reflection with a noticeable delay.
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Ultrasound is used in diagnostics and echolocation, taking into account the intensity and safety of the effect.
Answer
Problem #39
soundThe echo returned after 0.8 seconds. Speed of sound 340 m/s. Find the distance to the obstacle.
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Answer
The theory behind these problems
Work through the topic if a problem will not give in.
Formulas by topic
Look up symbols and units of measurement in the reference.