Some sample physics problems

These are based on the order found in
http://www.google.com/search?hl=en&q=REA%27s+%22Physics+Problem+Solver%22+%22Dr.+M.+Fogiel%22+

I. f * λ = v

  wave frequency * wavelength = wave velocity

  Calculator: http://www.sengpielaudio.com/calculator-wavelength.htm

(1a) The velocity of sound in air at 18'C (a common room temp) is 34,000 cm/sec
Is a 2-cm wave in air audible?
freq = velocity/length = 34,000/2 = 17,000 = 17 kHz
Yes. This is within the audible range (20 Hz - 20kHz)

Notes: Since sound is a compression wave its speed is proportional to temperature. The hotter the air, the closer the moecules are, and the faster a compression wave can travel through them. I need a solid reference for the audible range. Hz is cycles of vibration per second. kHz is 1000 cycles per second. Say [herts].


(1b) Here is a sample solved problem for radio waves, which uses the same equations:
"For example, radio station KUGN broadcasts at a frequency of 590 KHz. What is the wavelength of the radio wave?"
http://physics.uoregon.edu/~soper/Light/frequency.html