Question

You know by now very well the condition for rotational equilibrium is that the sum of all torques about any axis is zero. Let’s also consider it from translational standpoint for this lab. In our lab, the bar is also in translational equilibrium. Should you then expect the three forces involved,~FF P, mbar g,Fh, sum to zero? Why is that?

Answer 1

Yes, in case of transational equilibrium, i.e. the motion of the body is not accelerated. It eith moves with a constant speed or does not move at all. The sum of all the forces must be zero.

If the sum is not zero, then a net force acts and according to Newton's second law of motion,

F = ma

the force F will produce an acceleration 'a' in a body of mass 'm'.

As in equilibrium, there is no accleration, there should not be a net force and hence the sum of all forces must be zero.