
#1
Nov2004, 07:15 AM

P: 53

"There are two sine waves having a phase difference of 20 degrees. After one reaches its maximum value, how much time will pass until the other reaches its maximum, assuming a frequency of 60 Hz."
Should I go about this by assuming... sin(120pi*t) = sin(120pi(t + x)  20) Any hints appreciated 



#2
Nov2004, 08:04 AM

Sci Advisor
HW Helper
P: 2,004

You have two sines which have are functions of position and time. (actually, considering them function of time alone is sufficient)
They both have the form: [tex]A\sin(kx\omega t + \phi)[/tex] Assume the first wave reaches its maximum A at time t=0 and position x=0. Then you have to find t when the second wave reaches its max A: [tex]A\sin(\omega t + \phi)=A[/tex] Where [itex]\phi[/itex] is 20 degrees expressed in radians. 



#3
Nov2004, 08:34 AM

P: 53

I get it. Since 20 degrees = pi/9, moving LHS A to RHS gives
sin (120pi*t + pi/9) = 1 so, 120pi*t + pi/9 = pi/2 and finally t = 7/2160 seconds Many thanks 


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