# Will the block m2 move?

• B
Gold Member Suppose two blocks m1 and m2,connected by a spring are kept on a frictionless surface and the block m1 is applied an external force F.
My teacher taught me that in a spring the force is generated in the direction opposite to the displacement of the spring.
So the spring would generate a force in the left direction as it's displacement would be right.
So my question is that will the block m2 move in the *left* direction or not as a force is getting applied on it in the left direction?
I will be thankful for help!

## Answers and Replies

stockzahn
Homework Helper
Gold Member
What would happen, if the mass of block ##m_2## would be zero? What would be the force on ##m_1##? Try to apply Newton's 3rd law.

Gold Member
If mass of m2 is zero then block m1 would just move with acceleration F/m1.
What are you trying to explain?
What would happen, if the mass of block ##m_2## would be zero? What would be the force on ##m_1##? Try to apply Newton's 3rd law.

stockzahn
Homework Helper
Gold Member
If mass of m2 is zero then block m1 would just move with acceleration F/m1.
What are you trying to explain?

There only would be a force to the left acting on ##m_1## if there is a "counterforce" acting to the right on ##m_2##. From the perspective of ##m_2## the displacement of the spring would be to the left.

A.T.
Science Advisor
My teacher taught me that in a spring the force is generated in the direction opposite to the displacement of the spring.
Have you never compressed/stretched a spring with your hands? It should be obvious that it applies two opposite forces at both ends.

sophiecentaur
Science Advisor
Gold Member
2020 Award
The teacher's question is not tightly enough specified for a rigorous answer. This is not as harmless a fault as you might think because two different people could interpret it in two different ways.
If we assume that the spring is at its equilibrium length then what would cause any movement to the left if the input force F is to the right?
What do we know about the forces at each end of a light spring or a light string?

Doc Al
Mentor
My teacher taught me that in a spring the force is generated in the direction opposite to the displacement of the spring.
The spring resists being compressed or being stretched. Here, the spring is compressed and it will exert an outward force at each end.