Centripetal force facts for kids

An athlete needs centripetal force to make a good hammer throw.

Centripetal force is a special kind of force that pulls things towards the center when they are moving in a circle. Imagine you're swinging a ball on a string. The force that the string pulls on the ball, keeping it from flying away, is centripetal force. This force always points directly towards the center of the circle the object is making. It's what helps objects stay in a circular path.

Centripetal vs. Centrifugal Force

When an object moves in a circle, there are two important forces to understand.

What is Centripetal Force?

Centripetal force is the "center-seeking" force. It's the force that makes an object follow a curved path instead of going in a straight line. Without this force, the object would just fly off in a straight line, thanks to Isaac Newton's first law of motion (which says objects keep moving in a straight line unless a force acts on them).

What is Centrifugal Force?

The opposite of centripetal force is called centrifugal force. This is the "center-fleeing" force. It's the feeling you get when you're in a car turning a corner, and you feel pushed outwards. While centripetal force is a real force pulling towards the center, centrifugal force is more like an apparent force, a reaction to the centripetal force. It's the tendency of an object to want to continue in a straight line, even though it's being pulled into a circle.

For example, when you swing a heavy object on a rope, the rope becomes tight. The rope is providing the centripetal force, pulling the object towards your hand. The object, because of its inertia, wants to fly away in a straight line. This "wanting to fly away" is the effect of centrifugal force.

Centripetal Force in Action

Centripetal force is all around us!

Roller Coasters

Think about a roller coaster that goes through a loop. Centripetal force is what keeps the carts on the track, even when they are upside down at the top of the loop! The track pushes on the coaster, providing the necessary force to keep it moving in a circle. Even if the coaster's speed stays the same, its direction is constantly changing, which means it is always accelerating. This acceleration is caused by the centripetal force.

Planets and Satellites

The Earth orbits the Sun because of centripetal force. In this case, the force is gravity. The Sun's gravity pulls the Earth towards it, keeping our planet in its orbit. The same goes for the Moon orbiting the Earth, or satellites orbiting our planet. Gravity acts as the centripetal force, preventing them from flying off into space.

Spinning Objects

When you spin a washing machine, the water is removed from your clothes because of centripetal force. The drum of the washing machine provides the centripetal force on the clothes, pushing them towards the center. The water, however, is not held as tightly and tends to move outwards through the holes in the drum due to its inertia, getting spun out of the clothes.

Images for kids

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  This diagram shows how an object's direction changes when it moves in a circle.

See also

In Spanish: Fuerza centrípeta para niños