Centripetal acceleration
The inward acceleration that keeps something on a circle, a = v squared / r. It changes direction, not speed.
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Analogy
The pull of the string when you swing a ball round your head.
Example
a = v^2 / ra = 225 / 50a = 4.5 m/s^2
In practice
A car at 15 m/s on a 50 m radius bend accelerates inward at 4.5 m/s squared.
Practice
Flashcards
- What is the formula for centripetal acceleration?a = v^2 / r, pointing toward the centre.
Questions people ask
Is centripetal acceleration different from centrifugal force?
Centripetal means centre-seeking and describes the real inward acceleration. Centrifugal force is an apparent outward push felt inside a rotating frame, like being pressed against a car door in a turn. In an outside, non-rotating view, no outward force acts on you.
Does constant speed on a circle mean zero acceleration?
No. Velocity is a vector, and its direction keeps changing on a circle. A change in direction is an acceleration even if speed is steady. That acceleration points toward the centre and has a size of v squared over r.