Centripetal Force in Uniform Circular Motion

Steps:

• Uniform circular motion at constant speed means velocity changes direction, producing centripetal acceleration toward the circle's center.
• Newton's second law states resultant force equals mass times acceleration, so it acts in the acceleration's direction.
• The track's friction or banking provides this inward force to keep the car curving.
• Therefore, the resultant force direction is radially inward, toward the center.

Why D is correct:

• D points toward the center, aligning with the centripetal force formula F = mv²/r, which requires inward direction for circular path.

Why the others are wrong:

• A points tangential forward, indicating force for speeding up, not turning.
• B points radially outward, opposing the needed inward force and causing straight-line motion.
• C points tangential backward, suggesting braking force, not for direction change.

Final answer: D