Finding the Equations of Motion for a Mass-Spring System

lz975545
Messages
3
Reaction score
0

Homework Statement


A block is attached to the sides of a square box by 4 springs. The box is placed horizontally on a frictionless surface (ignore gravity). The mass of the block is ##m##, the natural length of each spring is ##l##, and the strength of each spring is ##k##. Place the block at ##(0,0)##. Let ## x(t), y(t)## the position of the block in time. Find the equations of motion of the block. (Use vectors to break each force up into its vertical and horizontal components)
https://www.physicsforums.com/attachments/196323

Homework Equations



##F = m\frac{d^2x}{dt^2} = -kx##

The Attempt at a Solution


[/B]
I'm just a little confused on how to start this problem. Would I use the distance formula from each wall to the block (wall to block to wall) on each axis?
 
Physics news on Phys.org
lz975545 said:
I'm just a little confused on how to start this problem. Would I use the distance formula from each wall to the block (wall to block to wall) on each axis?
Yes. If the coordinates of the block are (x,y), what are the lengths of the 4 springs? What is the change in length of each spring? What are magnitudes of the 4 forces? In terms of the unit vectors in the x and y directions (and x and y), what are the 4 unit vectors in the directions of the springs?
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top