- #1

PhySci83

- 7

- 0

## Homework Statement

A 2.0-kg mass (m1) and a 3.0-kg mass (m2) are on a horizontal, frictionless surface, connected by a massless spring with spring constant k = 140 N/m. A 15-N force (F) is app0lied to the larger mass, m2, as shown in the figure:

|__m1__|-/-/-/-/-|____m2____| ----------> F

Show that the magnitude of the spring force (spring tension) is given by:

F

_{s}= F(1/(1+(m2/m1))) <---Sorry, do not know how to make that look more asthetically pleasing.

## Homework Equations

F = ma

F

_{s}= -k(x

_{f}-x

_{i})

## The Attempt at a Solution

Since I am looking for the F

_{s}, I attempted to find the net force of the system with the direction of the force being the positive x direction and the N force of the masses being the positive y.

So for the F going to the right, I said F = (m1+m2)*a; a = F/(m1+m2).

For the F of the spring, I said F

_{s}= -k(x

_{f}-x

_{i}) and rearranged the equation so that delta_x = magnitude_F/K; delta_x=(ma)/K; then I plug in the value for a that I solved prior.

The problem is, I keep going around in circles with this thing. I am pretty far removed from basic HS math, but if the F wasn't pulled out of the equation, would it be:

F

_{s}= F/(F + [(F*m2/F*m1)])?

Any help that would point me in the right direction would be greatfully appreciated. It seems like I have to solve for the various variables and plug them into the original equation:

F

_{s}= -k(x

_{f}-x

_{i})

but getting rid of K and delta_x are troubling me.