Which of the following statements about a moving object is correct?

Step 1: Analyze the question We need to find the one true statement about a moving object, using Newton's laws of motion.

Step 2: The concept

• Newton's First Law: an object stays at rest or moves with constant velocity (steady velocity) in a straight line unless acted on by a non-zero resultant (net) force.
• Newton's Second Law: F = ma. If acceleration a = 0, then the resultant force F = 0. If a ≠ 0, then F ≠ 0.

Step 3: Check each option

• A. Wrong. When an object is accelerating, a ≠ 0, so F = ma ≠ 0. The resultant force cannot be zero.
• B. Wrong. An object can move at constant velocity with no resultant force. Motion does not need a net force to continue, only a change in motion does.
• C. Correct. Steady velocity means a = 0, so F = ma = 0. The forces may still exist, but they balance out. For example, a car cruising at constant speed has engine thrust equal to the total resistance.
• D. Wrong. At steady velocity, air resistance can still be present. It simply balances the driving force (or, for a falling object at terminal velocity, it equals the weight). It is not zero.

Step 4: Answer The correct statement is C: at a steady velocity, the resultant force is zero.

Tip: Remember "No acceleration means no resultant force." Do not confuse "no resultant force" with "no forces at all." Forces can be present but balanced. Also, WASSCE often tests the idea that force is needed to change motion, not to maintain it.