# Vertical 2 mass 2 spring problem - IVP

• tusch05
In summary, the conversation discusses a homework problem involving two masses connected by springs and an applied force. The goal is to find a solution using Euler's method over a time period of 0<=t<=10 sec. The correct initial conditions for the velocities are given and the equations for the accelerations are corrected. The Euler's method formula is used to find the positions and velocities of the masses over the given time period.
tusch05

## Homework Statement

mass1 = 10kg connected to ceiling by a spring
mass2 = 2kg connected to mass1 by a spring

2m/s is applied to mass 1 in the downward direction (positive direction) to get the system in motion
At equilibrium Mass 1 is 2m from the ceiling while mass 2 is 4m from the ceiling

10 x1’’ = -100x1 + 120(x2-x1)
2 x2’’ = -120(x2-x1)

find solution over time period 0<=t<=10sec

Need to use Eulers method

## The Attempt at a Solution

Reduce equations to:
x1’’ = 12x2-22x1
x2’’ = 60x1 – 60x2

Let:
x1’ = z
x1’’ = dz/dx
z(0) = 2 m/s ?

Let:
x2’ = v
x2’’ = dv/dt
v(0) = 0 m/s ?

dx1/dx = z = f1(x1,x2,z)
dz/dx = 12x2-22x1 = f2(x1,x2,z)
dx2/dx = v = f3(x1,x2,v)
dv/dx = 60x1 - 60x2 = f4(x1,x2,v)

Not sure if I have these initial conditions set up properly??
Please help, Thanks

Last edited:
!

Thank you for your post. It seems like you are on the right track with your solution attempt. However, there are a few things that need to be clarified and corrected in order to find a solution using Euler's method.

Firstly, the initial conditions for the velocities should be given in terms of the initial conditions for the positions. In this case, we are given the initial positions of the masses, but not their initial velocities. Therefore, we need to use the given information to find the initial velocities.

We know that mass 1 is initially at rest (x1' = 0) and it is given an initial velocity of 2 m/s in the downward direction (positive direction). This means that x1'' = -2 m/s^2. We can use this information to find the initial velocity of mass 2, which is connected to mass 1 by a spring. Since the spring is initially at equilibrium, we can assume that the initial velocities of mass 1 and mass 2 are equal, i.e. x2' = z = 2 m/s. This also means that x2'' = dz/dx = -2 m/s^2.

Therefore, the correct initial conditions for the velocities are:
x1' = 0 m/s
x1'' = -2 m/s^2
x2' = z = 2 m/s
x2'' = dz/dx = -2 m/s^2

Secondly, the equations for the accelerations (x1'' and x2'') are incorrect. The correct equations are:
x1'' = -120(x1-x2)/10 = -12(x1-x2)
x2'' = -120(x2-x1)/2 = -60(x2-x1)

Substituting these equations into the Euler's method formula, we get:
x1(t+h) = x1(t) + h*z(t)
z(t+h) = z(t) + h*(-12*(x1-x2))
x2(t+h) = x2(t) + h*v(t)
v(t+h) = v(t) + h*(-60*(x2-x1))

Now, we can use these equations to find the positions and velocities of the masses over the given time period (0<=t<=10 sec). I hope this helps. Let me know if you have any further questions. Good luck with your calculations!

I would first commend the student for attempting to solve the problem and using Euler's method to do so. However, I would also suggest that the student double check their initial conditions for x1' and x2' as well as their equations for x1'' and x2''. It may also be helpful to plot the equations and initial conditions to visually understand the system's behavior over time. Additionally, I would recommend checking for any errors or typos in the equations and initial conditions to ensure accurate results. Overall, it seems like the student is on the right track and with some minor adjustments, they should be able to successfully solve the problem.

## 1. What is a "Vertical 2 mass 2 spring problem - IVP"?

The Vertical 2 mass 2 spring problem - IVP refers to a specific type of mathematical model that is used to study the motion of two masses connected by two springs that are arranged vertically. It is an initial value problem, meaning that the initial conditions of the system are known and used to solve for the motion of the masses.

## 2. What are the key components of this problem?

The key components of the Vertical 2 mass 2 spring problem - IVP include the two masses, the two springs, and the gravitational force acting on the masses. Other factors such as the initial position and velocity of the masses, the stiffness of the springs, and the damping coefficient may also be included in the model.

## 3. How is this problem solved?

This problem is typically solved using differential equations, specifically the equations of motion for the masses. The initial conditions are used to set up the equations, which are then solved using techniques such as separation of variables, substitution, or numerical methods.

## 4. What are some real-life applications of this problem?

The Vertical 2 mass 2 spring problem - IVP has numerous real-life applications, including studying the motion of two connected objects, such as elevators or pendulums, and analyzing the behavior of structures with multiple springs, such as bridges or buildings.

## 5. What are some limitations of this problem?

One limitation of this problem is that it assumes ideal conditions, such as no external forces acting on the masses and perfectly linear springs. In reality, there may be other forces at play and the springs may not behave exactly as predicted by the model. Additionally, the problem may become more complex when more masses and springs are involved.

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