# Resultant force/equilibrium question?

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#1
In mechanics, if the equilibrium is zero, does this mean the particle can be going at a constant speed or stationary, or does it mean only one or the other?

Similarly, if the resultant force acting on a particle is zero, does this mean the particle is stationary or moving at a constant speed?

I keep confusing equilibrium and resultant force.
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2 years ago
#2
(Original post by Bertybassett)
In mechanics, if the equilibrium is zero, does this mean the particle can be going at a constant speed or stationary, or does it mean only one or the other?
If a particle is in equilibrium, that means all the forces on it cancel to give a net force of zero. This implies a zero acceleration for the particle (since mass cannot be zero). Which implies constant velocity.

But constant velocity can be =1 or =500 or =-2000 OR even =0.

So just because a particle is in equilibrium, we cannot deduce whether it is actually just 'moving with constant velocity' or 'is stationary'

Indeed the special case of velocity = 0 is often referred to as 'static equilibrium'

Similarly, if the resultant force acting on a particle is zero, does this mean the particle is stationary or moving at a constant speed?

I keep confusing equilibrium and resultant force.
Resultant force is just another way to say 'net force' so they're interchangeable. With what I said above, this would mean that resultant force of zero would imply constant velocity.
Last edited by RDKGames; 2 years ago
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