A sinusoidal wave is traveling on a string with speed 20. cm/s. The displacement
ID: 1704362 • Letter: A
Question
A sinusoidal wave is traveling on a string with speed 20. cm/s. The displacement of the particles of the string at x = 25 cm is found to vary with time according to the equation y = (5.0 cm) sin[10.0 - (8.0 s-1)t]. The linear density of the string is 7.0 g/cm.
(a) What is the frequency of the wave?
____s-1
(b) What is the wavelength of the wave?
_____ cm
(c) Give the general equation giving the transverse displacement of the particles of the string as a function of position and time.
y(x,t) = ( ____ cm) sin[( ____cm-1)x - ( ____s-1)t]
(d) What is the tension in the string?
_____ N
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Explanation / Answer
y = (5.0 cm) sin[10.0 - (8.0 s-1)t]
the general expression for the wave is: y(x,t) = ym sin(kx -t)
at x=25cm
y(x,t) = ym sin(k*25 -t)
compare with the expression: y = (5.0 cm) sin[10.0 - (8.0 s-1)t]
=8 rad/sec
f = /(2) = 1.27388 Hz
Since 25k = 10, then k=10/25 =0.4
Wave length = (2)/k = 6.28/0.4 =15.7cm
The amplitute ym = 5 cm
By substituting the values of k and into the general expression y(x,t) = (5.0 cm) sin[10.0 - (8.0 s-1)t]
since v=/k = (/)
the tension is =2 /k2
[(8^2)*7g/cm]/(0.4)^2 = 0.02800 N