When a body moves in a circle, it experiences two kinds of acceleration:
1) Centripetal Acceleration
- Always directed toward the center of the circle.
- Arises from the centripetal force—the minimum force needed to keep the body in circular motion.
- Magnitude: ac = v² / r = ω² r (toward the center).
2) Tangential Acceleration
- Always along the tangent to the path at the body’s position.
- Changes the speed of the body along the circular path.
- Magnitude: at = r α (tangent to the motion).
Types of Circular Motion
• Uniform Circular Motion (UCM):
- Speed remains constant (direction changes continuously).
- Therefore, at = 0; only centripetal acceleration acts.
• Non-uniform Circular Motion:
- Speed changes with time (both direction and magnitude change).
- Therefore, at ≠ 0 in addition to ac.
Conclusion: In UCM, the tangential acceleration is zero; in non-uniform circular motion, it is non-zero.
