Question

The equations for the rotational equilibrium for the meter stick in the image below is KX X > R W m m₂ m, W. W W

Answer 1

For the meter stick to be in rotational equilibrium, the clockwise moment about R should be equal to the anti clockwise moment about R.

Clockwise moment about R,

M = (W_{​​​​​​m} × X_{​​​​​​cm}) + (W_{​​​​​​2} × X_{​​​​​​2}) + (W_{​​​​3} × X_​3)

Anti clockwise moment about R,

M = (W_{​​​​​​1} × X_{​​​​​​1})

So,

(W_{​​​​​​1} × X_{​​​​​​1}) = (W_{​​​​​​2} × X_{​​​​​​2}) + (W_{​​​​​​m} × X_{​​​​​​cm}) + (W_{​​​​3} × X_{​​​​​​3})

Also, the net force acting in vertical direction should be 0.

So,

W₁ + W_{​​​​​​2} + W_{​​​​​​3} + W_{​​​​​​m} = R

These two equations are needed to find the condition for rotational equilibrium of the meter stick.