Critical Thinking
Making Generalizations A friend says that all mechanical waves must lose energy as they move through a medium because some energy is lost due to friction. Explain why this is true.
Forming Operational Definitions Two sound waves with different frequencies travel through a steel rod at the same speed. Explain by giving an operational definition of wave speed.
Relating Cause and Effect Can two waves traveling in the same direction form a standing wave? Explain why or why not.
Inferring The buzzing sound of a mosquito flying around your head has a higher pitch than the buzz of a bumblebee. What can you infer about the mosquito's wings compared to the bee's wings?
Relating Cause and Effect At the same time, you hear a kitten's purr and a clap of thunder. The kitten's purr is louder. Explain how this is possible.
Applying Concepts How much greater is the intensity of a 25-dB sound than a 15-dB sound? What would be the intensity in dB for a sound that is 100 times louder than the 25-dB sound?
Math Skills
Use the illustration below to answer Questions 30–32.
Interpreting Diagrams What is the wavelength of the ocean wave shown in the figure?
Evaluating Expressions Three complete wavelengths pass a fixed point once every 2 seconds. What is the frequency of the wave?
Calculating What is the speed of the ocean wave in Question 31?
Calculating A deep-water wave has a wavelength of 10.0 meters. If it travels at 3. 9 m/s, what is the wave's period?
Concepts in Action
Applying Concepts Some gardeners protect their gardens from animals by using sound that animals find irritating. Explain how the gardeners can tolerate the sound, while the animals cannot.
Formulating Hypotheses Generate a hypothesis about how the frequency of noise made by a machine changes as the machine operates at higher speeds.
Writing in Science Write a paragraph describing the motion of a lily pad as several waves from a boat pass by. Explain why the motion would be the same or different if the lily pad were floating free instead of attached by roots to the pond floor. (Hint: Before you write, draw a series of diagrams to show the motion.)
Performance-Based Assessment
Using Models Try blowing across the top of a bottle to produce a tone. Experiment to see how adding water of different heights affects the pitch. See if you can arrange a series of eight bottles to produce a musical scale. Learn to play a simple tune on your musical bottles. Summarize your results in a computer presentation that explains the relationship between the height of the air column and the pitch produced.
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