Understanding Mass-Spring Behavior in Zero Gravity

[aatari]

Hi Guys,

So I am using the following simulation for this activity (Mass and Springs).

The concept I need help with is to understand why when attaching a mass, the spring moves downward when the gravity is zero? If there is no gravity my limited understanding is that spring should not move.

Can someone please help me understand this phenomenon.

Thanks!

1. Homework Statement

How can you account for the behaviour of masses on springs when the force of gravity is zero? Give your answer both qualitatively (written explanation) and mathematically (algebraic explanation).

Homework Equations

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Fs = Fg
Fg = mg
Fs = k.x

The Attempt at a Solution

 

[scottdave]

When I went to the simulation website, it settled back to the dashed line for g=0. When you first hook it on, if you are not exactly on the equilibrium point then there will be some disturbance of the spring - note that you can use the hand to pull on the masses, then release and watch it oscillate.
If the spring is horizontal on a table, and you pull on it, you would expect it to exert a force back toward the equilibrium point.

 

[Merlin3189]

If you attach the masses without stretching or compressing the spring, there is no oscillation.

If you attach the mass and release it away from the neutral point, it oscillates because you have provided some potential energy by stretching or compressing the spring.

 

[aatari]

You guys are awesome. I actually took the spring disturbance as movement and this is obviously not the case. Using the ruler and dash line really helps. Thank you for the clarification.

 

[scottdave]

Try turning on the energy bar graphs to watch how energy changes between different forms (kinetic, gravitational PE (if gravity), spring PE, and thermal (from the friction)). It is interesting to watch how the bar graphs respond.