Difference between two harmonic motion equations

In summary, the conversation discusses two equations that are similar but have subtle differences in their applications. The first equation represents simple harmonic motion, while the second describes a traveling wave. The speaker is struggling to understand the difference and is seeking clarification.
  • #1
Rorshach
136
0

Homework Statement


Hello, folks:) I'm currently having problem with properly understanding the difference and aplications of two equations which resemble each other greatly, but the difference makes it difficult for me to tell exactly which one is for what.

2. Homework Equations

Those two equations are given below:
(1) x(t)=Asin(ωt+φ)
(2) y(x,t)=Asin(kx-ωt)

The Attempt at a Solution


I know it is silly, but it's like I have brick wall in my mind that just prevents me from getting it right.
My initial conclusions told me that first one describes dependence of displacement of a body(in my particular case I was interested in acoustic wave) from beginning of coordinates system from time. Second one describes displacement of a body on axis perpendicular to the axis of direction of propagation of a wave I am interested in (in the dircetion of an amplitude, so to speak). Now I am just confused, and cannot place my conclusions in any real life illustrations. Please help me in getting this right.
 
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  • #2
Rorshach said:
Those two equations are given below:
(1) x(t)=Asin(ωt+φ)
(2) y(x,t)=Asin(kx-ωt)
The second equation describes a traveling wave moving in the +x direction with some speed. y is the displacement of the wave at some position x and some time t.

The first equation can be used to describe the displacement of something in simple harmonic motion, where x is the displacement from equilibrium.

Let me know if that helps.
 

FAQ: Difference between two harmonic motion equations

What is the difference between simple harmonic motion and damped harmonic motion?

Simple harmonic motion is a type of periodic motion where the restoring force is directly proportional to the displacement from equilibrium. Damped harmonic motion, on the other hand, is a type of motion where the amplitude decreases over time due to the presence of a damping force. In simple harmonic motion, the system will continue to oscillate indefinitely, while in damped harmonic motion, the oscillations will eventually come to a stop.

How do the equations for simple harmonic motion and damped harmonic motion differ?

The equation for simple harmonic motion is x(t) = A*cos(ωt + φ), where A is the amplitude, ω is the angular frequency, and φ is the phase angle. The equation for damped harmonic motion is x(t) = Ae^(-bt)*cos(ω't + φ'), where b is the damping constant, ω' is the damped angular frequency, and φ' is the damped phase angle. The main difference is the presence of the damping constant and the damped angular frequency in the equation for damped harmonic motion.

Can the equations for simple harmonic motion and damped harmonic motion be combined?

Yes, the equations can be combined to describe a system with both simple harmonic and damping forces acting on it. The resulting equation would be x(t) = A*e^(-bt)*cos(ωt + φ), where A is the amplitude, b is the damping constant, ω is the angular frequency, and φ is the phase angle. This equation takes into account both the amplitude decay due to damping and the oscillatory motion due to the simple harmonic force.

How do the graphs of simple harmonic motion and damped harmonic motion differ?

The graph of simple harmonic motion is a sinusoidal wave with a constant amplitude and frequency. The graph of damped harmonic motion, on the other hand, shows a decaying amplitude over time due to the presence of the damping force. The frequency of oscillation may also be slightly different due to the damping effect.

What factors affect the difference between two harmonic motion equations?

The main factors that affect the difference between two harmonic motion equations are the presence of a damping force, the damping constant, and the initial conditions of the system (such as the initial amplitude and phase angle). The mass and spring constant of the system may also have an impact on the equations and resulting motion.

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