Harmonic oscillation, spring not attached to center of mass

In summary, the conversation discusses a bar that is guided to move on a vertical and horizontal line, with a spring attached to the upper end. Any friction is neglected. The goal is to find out how x varies in time, with x being the center of mass. The equation for x is given as x = A sin (√(k/m)t + φ0), but it is noted that the center of mass is now at the center of the rod instead of x. The equation of motion is questioned and it is suggested that Lagrange's equations may be the best approach. If not familiar with those equations, a good free body diagram is recommended.
  • #1
Antti
27
0
A bar is guided so that one end moves on a vertical line and the other on a horizontal line. A spring is attached to the upper end according to the figure. Any friction is neglected.

http://web.comhem.se/~u48800174/springbar.jpg

I want to find out how x varies in time. If the center of mass would have been at x and k is the spring coefficient and m the mass, then

[tex]x = A sin (\sqrt{k/m}t + \phi_{0})[/tex]

But now the center of mass is at the center of the rod (with length d) instead. More specifically:

[tex]\overline{CM} = (x/2, -\sqrt{d^2 - x^2}/2[/tex]

How does this affect the equation of motion? Is it perhaps still the same? My intuition tells me something would change when the spring isn't attached at the COM but i don't know what and why. Thankful for help!
 
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  • #2
This problem is easiest with Lagrange's equations.
If you don't know them, write a good free body diagram.
 

1. What is harmonic oscillation?

Harmonic oscillation is a type of motion in which a system or object moves back and forth between two points, with a constant period and amplitude. It is characterized by a sinusoidal or wave-like pattern.

2. How is harmonic oscillation related to springs?

Harmonic oscillation is often observed in systems involving springs, as springs have a natural tendency to return to their original position when stretched or compressed. This results in oscillation between two points, with the spring acting as the restoring force.

3. Can a spring be attached to a point other than the center of mass?

Yes, a spring can be attached to any point on an object, not just the center of mass. This will affect the period and amplitude of the oscillation, but the overall nature of the harmonic motion will remain the same.

4. How does the mass of an object affect harmonic oscillation with a spring?

The mass of an object affects the period of the harmonic oscillation, with a heavier object having a longer period and a lighter object having a shorter period. However, the amplitude of the oscillation remains unchanged.

5. What are some real-world examples of harmonic oscillation with a spring?

Some examples of harmonic oscillation with a spring include a pendulum, a mass on a spring, or a guitar string. These systems exhibit harmonic motion due to the spring's restoring force and can be observed in everyday life.

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