One of the conditions necessary for an object to be in equilibrium when acted upon by a number of parallel forces is that the vector sum of the forces is? by Sunday | Nov 6 | Physics JAMB | 0 comments A. Average B. Zero C. Negative D. Positive Correct Answer: Option B – Zero Users Also Read These:If an object is placed between two parallel plane…An object is acted upon by a system of parallel…What happens when three coplanar non-parallel forces…The diagram below illustrates three forces acting on…A piece of cork floating on water is acted upon by…