With which forces and why spring acts on two bodies

[harmyder]

Homework Statement

Suppose we have spring which is between two bodies of different mass, with which force spring will act on every of them?

Homework Equations

Spring acts on a body with force $kx$

The Attempt at a Solution

A-/\/\/\/\/\/\/\-B
Suppose body A has mass 2kg and body B has mass 1kg, i think spring will act on body A with force $kx$ and on body B with the same force, but i don't understand why? Why not $kx/2$?

 

[Eclair_de_XII]

Suppose body A has mass 2kg and body B has mass 1kg, i think spring will act on body A with force $kx$ and on body B with the same force, but i don't understand why? Why not $kx/2$?

I think Newton's Third Law explains this. The spring exerts a force $kx$ on $B$ and in turn, $B$ exerts a force $-kx$ on the spring. Then the spring transfers that force $-kx$ to $A$, and in turn, $A$ pushes back on the spring with the force $kx$ which gets transferred to $B$ and so on and so forth. Can someone correct me on this or explain this more clearly so that he can understand?

 

[Nidum]

There is not enough information given in the problem statement for any definite answer to be arrived at .

 

[harmyder]

There is not enough information given in the problem statement for any definite answer to be arrived at .

Sorry, what additional information should i provide?

 

[haruspex]

I think Newton's Third Law explains this. The spring exerts a force $kx$ on $B$ and in turn, $B$ exerts a force $-kx$ on the spring. Then the spring transfers that force $-kx$ to $A$, and in turn, $A$ pushes back on the spring with the force $kx$ which gets transferred to $B$ and so on and so forth. Can someone correct me on this or explain this more clearly so that he can understand?

Looks right to me.
This confuses many students. The root of that, in my view, is that a tension (or compression) is not so much a force as a pair of equal and opposite forces.