JAMB Physics 2019 Paper

Concept:For equilibrium, the net force and the net moment acting on the object must each be zero.Explanation:Equilibrium of parallel forces requires that the resultant force is zero, so $\sum F = 0$.This means the sum of forces in one direction must equal the sum of forces in the opposite direction: $\sum F_{\text{up}} = \sum F_{\text{down}}$.It also requires that the algebraic sum of all moments is zero: $\sum \tau = 0$.However, equilibrium does not require every component force to be equal in magnitude and direction.If all the parallel forces were equal and acting in the same direction, their resultant would not be zero, so equilibrium would be impossible.Therefore, the statement claiming that all parallel forces must be equal in magnitude and direction is false.Answer:The incorrect statement is: all the parallel forces must be equal in magnitude and direction.