# Condition for equilibrium

1. Jan 28, 2012

### spaghetti3451

Can a body be in equilibrium if only one force acts on it? I think it can't, if the force is non-zero. Thoughts?

2. Jan 28, 2012

### Staff: Mentor

What do you think?

3. Jan 28, 2012

### kmarinas86

Re: Condition for (force) equilibrium

The following is what "failexam" thought:

4. Jan 28, 2012

### Staff: Mentor

Makes sense to me.

5. Jan 28, 2012

### spaghetti3451

Well, I think the body can't be in equilibrium. That's the obvious answer. But I'm wondering if this might be a trick question. So ...

6. Jan 28, 2012

### spaghetti3451

I see. Not a trick question, then!

7. Jan 28, 2012

### Studiot

Perhaps there is a twist to this question.

Can a body be said to have only one force acting one it?

Considering that any force can be resolved into component forces.

So perhaps we could talk about one net force or a non zero resultant or that there is a (single) resultant.

You have entitled this thread 'conditions for equilibrium' , so presumably that is what you are reading.

So perhaps the text is a bit slack and should read something like the conditions for a body to be in force equilibrium is that the resultant of any applied forces is zero or that the components are separately zero.
Moment equilibrium is something else again that should be considered.

8. Jan 28, 2012

### Staff: Mentor

I think the question is clear enough. A single non-zero force acts on a body. (Sure, you can break that force into components, but so what?) Can the body be in equilibrium? No.