WAEC Physics 2010 Paper

Concept:Dynamic equilibrium of a moving particle means the resultant force is zero and the particle moves with constant velocity.Explanation:When the resultant force acting on a particle is zero, Newton's second law gives $F_{\text{net}} = ma = 0$.Therefore, acceleration is zero and the velocity of the particle does not change.Since the particle is already moving, it continues to move with uniform velocity.This condition is called dynamic equilibrium.Option B is incorrect because a resultant force greater than zero causes acceleration, not uniform velocity.Option C is incorrect because the rate of change of momentum acts in the direction of the resultant force, not opposite to motion.Option D is incorrect because a freely falling particle accelerates and covers unequal distances in equal time intervals.Thus, the correct statement is Option A.Answer:A. If the resultant force acting on the particle is zero, then it is in dynamic equilibrium.