Help Needed: Deriving Expressions for Mass-Spring System

In summary, the conversation is about deriving expressions for a mass-spring system in series. The first equation involves finding Keq and is a common expression. The participants discuss using similar thinking for all three equations and using the formulas for tension and extension. They also mention the relationship between the tension in each spring and the displacement of the springs from their unstretched positions.
  • #1
chocofingers
30
0
Could somebody help me in deriving the following expressions?
I can judge that the first equation is a common expression for finding Keq for a mass-spring system in series.. Can't do the rest :/ anybody please ?

Thanks in advance.
 

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  • #2
Show how you would derive the first equation. You'd use similar thinking for all three.
 
  • #3
I don't know how to derive the first equation... If you could help me though for all the three... :)
 
  • #4
You give it a try. Hint: What's the relationship between the tension in each spring?
 
  • #5
Doc Al i gave it a try. I know the formulas ... tension(F) = k x e(extension) ...
so K1 e1 = K2 e2

Next what to do ?
 
  • #6
chocofingers said:
I know the formulas ... tension(F) = k x e(extension) ...
so K1 e1 = K2 e2
Good! Now realize that e1 = x1 and e2 = x2 - x1.
 
  • #7
what is x1 and x2 ? is x1 the extension of spring e1 ? then what is x2?
 
  • #8
sorry i mean x2?
 
  • #9
chocofingers said:
what is x1 and x2 ? is x1 the extension of spring e1 ? then what is x2?
I'd say (just from looking at the equation) that x1 is the displacement of the end of spring one from its unstretched position and x2 is the displacement of the right side of spring two from its unstretched position. Since the left side of spring one is fixed, x1 happens to equal the amount of stretch of spring one.
 

1. How do you derive the equations of motion for a mass-spring system?

To derive the equations of motion for a mass-spring system, we use Newton's Second Law of Motion, which states that the sum of all forces acting on an object is equal to its mass times its acceleration. We also use Hooke's Law, which states that the force applied by a spring is directly proportional to its displacement from its equilibrium position. By combining these two laws, we can derive the equations of motion for a mass-spring system.

2. What are the variables and constants used in the equations of motion for a mass-spring system?

The variables used in the equations of motion for a mass-spring system are the mass of the object (m), its displacement from equilibrium (x), its velocity (v), and its acceleration (a). The constants used are the spring constant (k), which is a measure of the stiffness of the spring, and the gravitational constant (g), which is a measure of the force of gravity on the object.

3. What is the significance of the equilibrium position in a mass-spring system?

The equilibrium position in a mass-spring system is the point at which the force applied by the spring is equal to the force of gravity on the object. This is the point where the object is at rest, and any displacement from this position will result in a restoring force from the spring, causing the object to oscillate back and forth.

4. How can the equations of motion for a mass-spring system be used to solve real-world problems?

The equations of motion for a mass-spring system can be used to solve various real-world problems, such as determining the period and frequency of oscillation, calculating the maximum displacement and velocity of the object, and predicting the behavior of the system under different conditions. These equations are also used in various fields, such as engineering, physics, and mechanics, to analyze and design systems that involve springs and oscillating objects.

5. Are there any assumptions made when deriving the equations of motion for a mass-spring system?

Yes, there are certain assumptions made when deriving the equations of motion for a mass-spring system. These assumptions include: the mass of the object is concentrated at a single point, the spring is ideal and follows Hooke's Law, there is no air resistance or damping force, and the system is in a vacuum. These assumptions may not hold true in all real-world scenarios, but they provide a simplified model for analyzing and understanding the behavior of a mass-spring system.

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