# college physics

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have a couple of questions about my homework and it's due at midnight tonight:

1. On a hot summer day, the temperature of air in Arizona reaches 115°F. What is the speed of sound in air at this temperature? (Enter your answer to four significant figures. The speed of sound at 0°C is 331 m/s. Use the conversion 0°C = 273 K as necessary.)
I changed F to K (got 315.928) and I plugged it in the appropriate equation:
331m/s(315.928/273)^(1/2) and I got 356.1. This is not right what do I do?

2.A dolphin located in sea water at a temperature of 25°C emits a sound directed toward the bottom of the ocean 105 m below. How much time passes before it hears an echo?
I did two different equations: dividing 105 by the temp in K, then I tried 331(298K/273 k)^(1/2) then I multiplied it by to (to denote that the sound had to return back) and got 0.607 but that wasn't right.

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