A long string carries a wave; a 5.60-m segment of the string contains four compl
ID: 1510119 • Letter: A
Question
A long string carries a wave; a 5.60-m segment of the string contains four complete wavelengths and has a mass of 180 g. The string vibrates sinusoidally with a frequency of 45.0 Hz and a peak-to-valley displacement of 12.0 cm. (The "peak-to-valley" distance is the vertical distance from the farthest positive position to the farthest negative position.)
(a) Write the function that describes this wave traveling in the positive x direction. (Use the following as necessary: x and t. x is in meters and t is in seconds. Enter your numerical coefficients to four significant figures.)
y = ?
(b) Determine the power being supplied to the string.
? W
Explanation / Answer
peak tp valley distance = 12 cm
so A = 6 cm = 0.06 m
w = 2*pi*f = 2*3.14*45 = 282.6 rad/s
there are 5 waves in 5.60 m long segment
so lambda = 5.60/5 = 1.12 m
wave number k = 2*pi/lambda = 2*3.14/1.12
k = 5.60 rad/m
wave traveling in the positive x direction
y(x,t) = A*sin(w*t + k*x)
y(x,t) = 0.06*sin(282.6*t + 5.60*x)