Question
A wave in a string has an amplitude of 2 cm. The wave travels in the +ve direction of x -axis with a speed of 128 ms-1 and it is noted that 5 complete waves fit in 4 m length of the string. The equation describing the wave is
-
y = (0.02) m sin (7.85 x +1005t)
-
y = (0.02) m sin (15.7 x -2010t)
-
y = (0.02) m sin (15.7 x + 2010t)
-
y = (0.02) m sin (7.85 x - 1005t)
Solution
D.
y = (0.02) m sin (7.85 x - 1005t)
Find the parameters and put in the general wave equation.
here, A = 2 cm
direction = + ve x direction
v = 128 ms-1
and 5 λ = 4
k = 2π / λ = 2π x 5/4 = 7.85
and v = ω / k = 128 ms-1
ω = v s k = 128 7.85 = 1005
as y = A sin (kx - ωt)
y = 2 sin (7.85 x - 1005 t)
= 0.02 m sin (7.85 x -1005 t)
y = 2 sin (7.85 x - 1005 t)
= 0.02 m sin (7.85 x -1005 t)
