Circular Motion: Centripetal & Centrifugal Forces

Centripetal Force The force that makes a body follow a curved path, i.e. maintain uniform circular motion The direction of this force is always towards the centre of the circle Vector quantity Unit = newton

F = mω²r F = centripetal force m = mass of the body ω = angular velocity r = radius of rotation

F = mv²/r F = centripetal force m = mass of the body v = linear velocity r = radius

Examples of Centripetal Forces Car turning a corner = friction Planet orbiting the sun = gravity Object twirling on a string = tension All of these forces are centripetal and act towards the centre of the circular path Without a centripetal force, circular motion does not occur

Centrifugal force For every action there is an equal and opposite reaction, according to Newton's third law of motion So, centripetal force must have an opposing force keeping the balance, making sure the object is maintained in circular motion Centrifugal force balances out the centripetal force when an object is in circular motion The direction of the centrifugal force is away from the centre of the circular path Centrifugal force is the force that you feel when you are on a roller coaster, and if you weren't strapped in, this force would propel you from the seat.

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