Does a Spring Move Upward or Downward When the Box Stops?

[collegeconfid]

Homework Statement

A spring (in equilibrium) is attached to the top of a box that is moving at a constant speed vertically upward.
However, if the box stops, does the spring go upward or downward?

Homework Equations

The Attempt at a Solution

The spring goes downward because originally, the force being exerted on the spring is the spring force and gravity. But, when the box is stopping, there must be an extra downward force to slow the box down, so once the box stops, there will be a net downward force.

Logically, I would imagine the spring going upward but...

The answer is that the spring will go downwards. Is this the correct reasoning?

All replies are much appreciated.

EDIT: Sorry if I wasn't clear enough before, but the spring is inside the box and is hanging from the top of the box.

 

[ideasrule]

The spring goes downward because originally, the force being exerted on the spring is the spring force and gravity. But, when the box is stopping, there must be an extra downward force to slow the box down, so once the box stops, there will be a net downward force.

That's true, but a net downward force means a downward acceleration. It doesn't mean a downward speed.

Logically, I would imagine the spring going upward but...

That's correct. The spring initially keeps whatever speed it had before the box stopped, so it's still going upward when the box stops.

 

[kerimek]

Your reasoning is correct. When the box is moving at a constant speed upward, the spring is in equilibrium and experiencing a net upward force from the spring force and gravity. However, when the box stops, there is an additional downward force acting on the spring to slow the box down. This results in a net downward force on the spring, causing it to move downward. This can also be explained by Newton's first law of motion, which states that an object in motion will remain in motion unless acted upon by an external force. In this case, the external force of the box stopping causes the spring to move downward.