Harmonic Motion in One dimension -- Question in equation derivation

In summary, the conversation is about the second line of an equation being equal to the third line, and the confusion about the sign and its relation to Euler. The conversation also mentions using the angle addition/subtraction formula and questions the relevance of the second line.
  • #1
Futurestar33
29
0

Homework Statement


I am curious as to how the second line in the equation is equal to the third line in the equation. The book my class is using is Taylor and it just skips so many steps. What happens to the sign, I know this must relate to euler in some way I am just not sure how. Thank you
367-5-5P-i36.png

I am just curious as to why and how

Homework Equations

The Attempt at a Solution

 
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  • #2
Futurestar33 said:

Homework Statement


I am curious as to how the second line in the equation is equal to the third line in the equation. The book my class is using is Taylor and it just skips so many steps. What happens to the sign, I know this must relate to euler in some way I am just not sure how. Thank you
367-5-5P-i36.png

I am just curious as to why and how

Homework Equations

The Attempt at a Solution

Hello Futurestar33. Welcome to PF !

Use angle addition/subtraction formula on cos(ωt - δ) .
 
  • #4
I don't see why they include the second line, seems irrelevant since cos(theta) = cos(-theta)
 
  • #5
Thank you guys
 

FAQ: Harmonic Motion in One dimension -- Question in equation derivation

1. What is harmonic motion in one dimension?

Harmonic motion in one dimension refers to the back-and-forth motion of an object along a straight line, where the object's acceleration is directly proportional to its displacement from a central equilibrium point. This type of motion follows a sinusoidal pattern and is commonly seen in pendulums, springs, and other oscillating systems.

2. What is the equation for harmonic motion in one dimension?

The equation for harmonic motion in one dimension is x = A cos(ωt + φ), where x is the displacement from the equilibrium point, A is the amplitude of the motion, ω is the angular frequency (related to the period of the motion), and φ is the phase angle.

3. How is the equation for harmonic motion derived?

The equation for harmonic motion can be derived using Newton's second law of motion, which states that the sum of forces acting on an object is equal to its mass times its acceleration. By considering the forces acting on an object in harmonic motion (such as gravity and spring force), we can derive the equation x = A cos(ωt + φ) as a solution to the differential equation of motion.

4. What is the significance of the amplitude in harmonic motion?

The amplitude in harmonic motion represents the maximum displacement of the object from its equilibrium point. It is a measure of the object's energy and determines the height and width of the oscillations. The larger the amplitude, the more energy the system has, and the farther it will move from the equilibrium point.

5. How does the frequency of harmonic motion affect the motion of an object?

The frequency of harmonic motion, which is related to the angular frequency ω, determines how quickly the object oscillates back and forth. A higher frequency means the object completes more cycles in a given time, resulting in faster motion. The frequency is also inversely proportional to the period of the motion, so a higher frequency corresponds to a shorter period.

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