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There are countless of hilarious youtube videos like this one here, in which you can see that the carousel causes people to be pulled outwards.

  • What force is actually working on them, and why does it pull them outwards (instead of for example inwards)?

  • Can you give me some other (notable) example of this force in everyday life?

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3 Answers

up vote 1 down vote accepted

It's called the centrifugal force. An object that's in motion (with velocity in a certain direction) will tend to remain in motion in that direction (Newton's first law). If the object is tethered to a stationary point (by a rope, say), the tension of the rope continuously changes the direction of the object's velocity, which creates circular motion. It also creates a "force" exerted on the object, since the object "wants" to continue moving in a straight line (inertia), but the rope is causing it to change its direction. If the rope breaks, the object would fly off tangentially to the last point when the rope was intact.

On a carousel, a person's arms holding on to the railings represents the "rope". When this connection breaks, the person will fly off tangentially to the carousel.

Other notable examples include:

  • Planetary orbits... the centrifugal force on the planets is balanced out by the sun's gravity.

  • Clay on a pottery wheel... if you spin the wheel too fast, the clay will fly off.

  • A centrifuge in a laboratory.

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You mean centripetal force here "Planetary orbits... the centrifugal force on the planets is balanced out by the sun's gravity." –  namehere Nov 30 '12 at 11:06
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It's called the sudden absense of Centripetal Force

Newton's first law says that a person falling out of a carousel will continue to move in a straight line (i.e. tangential to carousel rotation) until some other force is applied (friction with asphelt, impact with wall).

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The answer is centrifugal force. It's not an actual force though, rather, it's an apparent force.

For example, if a person X is on a rotating platform (such as the one in the video) that rotates at a constant angular speed, an external viewer will see X do a uniform movement. But X, while seeing himself as immobile in the carousel, will perceive a force that drags him out (the centrifugal force) that pulls him away from the center of the carousel, which is balanced by the constraint reaction (not sure how it translates into English). Anyway, the only actual force here is this last one, the other one is apparent.

In any case, this is really a basic explanation and if someone can help me improve it, it'd be great.

An example in real life is when you enter a bend while inside the car. If you turn right, the centrifugal force will pull you (the body) to the left. Again: the force doesn't exist, it's only apparent.

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Why was this downvoted? Is there anything wrong stated? –  Alenanno Nov 30 '12 at 14:35
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