# Rotational and translational equilibrium

1. Feb 24, 2012

### sgstudent

When a ruler is placed on a pivot and I push it down from one side, then there is a moment. But then is there any linear movement? Since there is no translational equilibrium then won't there be a linear motion? Then how does rotational equilibrium come into play here?

2. Feb 24, 2012

### tiny-tim

hi sgstudent!
i don't understand

if you push it, it will change position …

where does equilibrium come into it?

3. Feb 24, 2012

### sgstudent

Oh sorry! I meant that when I push one side of a ruler on a pivot then I'll get a moment that is either clockwise or anticlockwise right? But since there only that downwards force acting on it, won't it mean that it does not have translational equilibrium?

4. Feb 25, 2012

### tiny-tim

hi sgstudent!
(just got up :zzz:)
ah!

but nature automatically supplies an upward reaction force at the pivot …

which exactly balances the downwards force!

5. Feb 25, 2012

### sgstudent

Oh, I understand :-) thanks for the help!