A wave given by y = 21 cos( 0.049 x - 310 t ), with x and y in mm and t in secon

Question

A wave given byy=21cos(0.049x-310t), withxandyin mm andtin seconds, is propagating on a cable with mass per unit length410g/m. a.) Find the Amplitude in mm. b.) Find the Wavelength in cm. c.) find the frequency in Hz. d.) Find the wave speed in m/s. e.) Find the power carried by the wave in W.

Explanation / Answer

E = hc / ? = hf -----> c / ? = f E = energy h = plancks constant = 6.626x10^-34 J s c = speed of light = 3.00x10^8 m/s ? = wavelength f = frequency and also note that 1 Hz = 1 / s...recipricol second... *** 1 *** c / ? = f ? = c / f = (3.00x10^8 m/s) / (8.67x10^9 / s) = 0.0346 m 0.0346 m x (1000 mm / 1 m) = 34.6 mm *** 2 *** c / ? = f ? = 32.2 cm x (1 m / 100 cm) = 0.322 m f = c / ? = (3.00x10^8 m/s) / (0.322 m) = 9.32x10^8 /s = 9.32x10^8 Hz ****** comments ******* i left plancks constant and energy etc for your future reference.. it really wasn't needed for this problem so you could skip those if you want. I know your question was about the unit conversions. not the formula of c / ? = f.. but I wanted you to see how the calculations should look. as to unit conversions... the process that I recommend is "factor label method".. aka "unit factor method"... aka "dimensional analysis"... it is extremely important that you understand this and practice it. here's a link to a question where I explained that process...it should take you about 10 minutes to read it. Please do so. It will make unit conversions easy...

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