1. A periodic wave has a period of 0.50 s. What is the wave frequency? 2. Waves moving on a lake have a speed of 3 m/s and a distance of 1.75 m between adjacent crests. a. What is the frequency of the waves? b. What is the period of the waves? 3. A sound wave has a frequency of 2500 Hz. What is the distancce between crests or compressions? (Assume that the speed of sound is 344 m/s.) 4. Compute the wavelength in air of ultrasound with a frequency of 60 kHz if the speed of sound is 344 m/s, 5. During a thunderstorm, a 5.5 s difference between observing a lightening flash and hearing the resultant thunder. How far away in km and mi was the lightening flash? (The speed of sound is 344 m/s) 6. A sound wave has a frequency of 250 Hz and a wavelength of 2.5 m. What is the speed of the wave? 7. The upper limit for human hearing is about 20,000 Hz. What is the wavelength, in m for this wave? 8. An echo is heard from a building 8 s after you blow the cars horn. How far away is the building? 9. The distance between the center of condensation and the center of an adjacent rarefaction is 5 m. If the frequency is 300 Hz, what is the speed of the wave front? 10. A sonar signal is sent from a ship and the signal returns from the bottom 3.75 s later. How deep is the ocean if the speed of sound in water is 1,530 m/s?

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the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

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im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.

bacteria that live on the ocean floor are sustained by phytoplankton. phytoplankton, microscopic marine photosynthetic organisms, have a vastly significant role to play not only in the marine food web of which they’re part of, but also on a more global scale. despite their infinitely small size in comparison to other marine organisms, these tiny creatures occupy an immensely important ecological niche: they are the foundation of the marine food web, and as primary producers, play key roles in supporting all other organisms in the marine environment, as well as in the regulation of the earth’s climate through the sequestration of carbon, oxygen production, and other related processes. phytoplankton account for roughly half of all global primary productivity; therefore, their significance extends far beyond the marine environment alone. there is an intriguing sense of irony in the realization that these tiny living beings that often live out their existence unnoticed and undetected by the rest of the world, have such a far-reaching impact on the lives of virtually all other living organisms on the planet, particularly on those in the marine environment. the world that we have become accustomed to has been and is continuously shaped by the workings of these miniscule yet vital “plants of the sea”.

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answer(20) psi;