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Phase constant of SHM

  • Thread starter 1MileCrash
  • Start date
  • #1
1,331
45

Homework Statement



The displacement of a mass oscillating on a spring is given by x(t) = xmcos(ωt + ). If the initial displacement is zero and the initial velocity is in the negative x direction, then the phase constant is:

Homework Equations





The Attempt at a Solution



How do I start? The book just tells me that the phase constant depends on displacement and velocity when t = 0, but doesn't say how.
 

Answers and Replies

  • #2
gneill
Mentor
20,792
2,770
Sketch a cosine curve. What's its initial value? Where on the curve would match the initial condition of the spring and mass? What's (angular) the offset from zero?
 
  • #3
1,331
45
Sketch a cosine curve.
OK

What's its initial value?
1

Where on the curve would match the initial condition of the spring and mass?
Huh??
 
  • #4
gneill
Mentor
20,792
2,770
Does the mass start at a maximum extension like the cosine function does?
 
  • #5
1,331
45
No, initial displacement is 0. So, I need to find where cosx equals 0?
 
  • #6
gneill
Mentor
20,792
2,770
No, initial displacement is 0. So, I need to find where cosx equals 0?
Not only that, but where it's going through zero and going negative, just like the mass' displacement.
 
  • #7
1,331
45
Still have no clue on this.
 
  • #8
gneill
Mentor
20,792
2,770
Have a gander:

attachment.php?attachmentid=40822&stc=1&d=1320887764.jpg
 

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