You're spinning a ball on a string in a horizontal circle above your head. The string suddenly snaps.
Which direction does the ball fly?
The ball flies tangent to the circle — the direction it was already moving when the string broke. There is NO outward force. The string was pulling INWARD to keep it on the circle.
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Watch the velocity vector — it's always tangent. Tap to release the ball and see where it goes.
a = v²/r
Double the speed → quadruple the required centripetal force. That's why highway curves are banked more steeply for higher speed limits.
At the top of a roller coaster loop, you need v² ≥ gr to stay on the track. Go slower, and you fall!
A washing machine spins clothes at ~1000 RPM. Water flies out tangentially through holes — it doesn't have enough 'inward force' to stay.
Earth moves at 30 km/s but gravity provides just enough centripetal force to curve our path into an orbit rather than a straight escape.
“There is no centrifugal force. Your body wants to go straight; the seat pushes you inward. Feel the push — that's the real force.”
Circular Lab
Adjust speed and radius to see how centripetal acceleration changes. Release the ball at any point.
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Double the speed and watch the acceleration arrow grow to 4× its length (a = v²/r). Then double the radius — it halves.
The velocity vector and acceleration vector are ALWAYS perpendicular in uniform circular motion. Acceleration changes direction, not speed.