🔋college physics i – introduction review

V²/r

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

The term v²/r represents the centripetal acceleration experienced by an object moving in a circular path. It is the formula that describes the acceleration directed toward the center of the circular motion, which is responsible for maintaining the object's curved trajectory.

5 Must Know Facts For Your Next Test

  1. The term v²/r represents the magnitude of the centripetal acceleration experienced by an object moving in a circular path.
  2. Centripetal acceleration is directed toward the center of the circular motion and is responsible for the object's change in direction, not its change in speed.
  3. The value of v²/r is directly proportional to the object's speed (v) and inversely proportional to the radius (r) of the circular path.
  4. Centripetal acceleration is a vector quantity, meaning it has both magnitude and direction, and it is always directed toward the center of the circular motion.
  5. The centripetal force, which provides the necessary acceleration to maintain the circular motion, is equal to the product of the object's mass and its centripetal acceleration.

Review Questions

  • Explain the relationship between the object's speed (v) and the radius (r) of the circular path in the context of centripetal acceleration (v²/r).
    • The centripetal acceleration, represented by the term v²/r, is directly proportional to the square of the object's speed (v²) and inversely proportional to the radius (r) of the circular path. This means that as the object's speed increases, the centripetal acceleration also increases, and as the radius of the circular path increases, the centripetal acceleration decreases. This relationship is crucial in understanding the dynamics of circular motion and the forces that act on an object moving in a circular trajectory.
  • Describe the role of centripetal acceleration (v²/r) in maintaining the circular motion of an object.
    • Centripetal acceleration, represented by the term v²/r, is the acceleration directed toward the center of the circular path, which is responsible for the object's change in direction. Without this centripetal acceleration, the object would continue to move in a straight line due to its inertia, rather than following a circular trajectory. The centripetal acceleration is the result of a centripetal force, which acts on the object and provides the necessary acceleration to keep it moving in a circular path. This centripetal force is what ultimately causes the object to change direction and maintain its circular motion.
  • Analyze how the magnitude of centripetal acceleration (v²/r) would change if an object's speed (v) or the radius (r) of its circular path were altered.
    • If an object's speed (v) increases while the radius (r) of its circular path remains constant, the centripetal acceleration (v²/r) will increase proportionally to the square of the speed. This means that doubling the speed will result in a four-fold increase in the centripetal acceleration. Conversely, if the radius (r) of the circular path increases while the speed (v) remains constant, the centripetal acceleration (v²/r) will decrease inversely proportional to the radius. This demonstrates the critical role that both speed and radius play in determining the magnitude of the centripetal acceleration experienced by an object moving in a circular motion.