Understanding the Phase Constant in Simple Harmonic Motion

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SUMMARY

The phase constant in simple harmonic motion is determined by both the initial displacement and the initial velocity of the mass. In the case where the initial displacement is zero and the initial velocity is negative, the phase constant can be calculated by identifying the point on the cosine curve where the cosine function equals zero and the velocity is negative. This corresponds to a phase constant of π/2 radians, indicating that the mass is moving downward through the equilibrium position at t=0.

PREREQUISITES
  • Understanding of simple harmonic motion concepts
  • Familiarity with the cosine function and its properties
  • Knowledge of angular displacement and phase constants
  • Ability to interpret initial conditions in oscillatory systems
NEXT STEPS
  • Study the derivation of the phase constant in simple harmonic motion
  • Learn how to graph cosine functions and identify key points
  • Explore the relationship between displacement, velocity, and phase in oscillatory systems
  • Investigate the effects of varying initial conditions on phase constants
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and oscillatory motion, as well as educators teaching concepts related to simple harmonic motion.

1MileCrash
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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.
 
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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?
 
gneill said:
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??
 
Does the mass start at a maximum extension like the cosine function does?
 
No, initial displacement is 0. So, I need to find where cosx equals 0?
 
1MileCrash said:
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.
 
Still have no clue on this.
 
Have a gander:

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

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