The Mystery of Centripetal and Centrifugal Forces


In my last few articles, I explained about inertia and frames of references. Following that path of exploration, we stop here at a strange place with two forces called centripetal and centrifugal respectively.

Centripetal forces

When an object is rotating around a point with constant angular speed, it is constantly pulled inwards towards the center of rotation. This inward force is called as the centripetal force.

Why centripetal force exists?

In contrast to what you have read in most of the physics textbooks, centripetal forces are real forces and they are the reason why an object follows a circular path. The source of this force can either be a string that is attached to the ball that’s rotating or the more common gravity. Centripetal force is what keeps the earth in its orbit around the sun.

Centrifugal forces

This is by far the most confusing force ever. Newton’s third law states that for every action there is an equal and opposite reaction. So if there exists a force that pulls a ball inward (through the string), there should also be an equal force acting upon the body in the other way. Nevertheless, it is not what happens exactly here. When an object is rotating, only its speed is constant. But the direction changes at every instant. This change in velocity means that the ball is accelerating. The ball has inertia and it wants to resist the change in motion. This inertia, if there is no centripetal force acting on the ball, will make the ball go outwards in a tangential direction. Therefore, this fictitious feel of a force (which is actually inertia) is what people usually refer as centrifugal force.

Always remember that centripetal forces exerts a pull towards the center and centrifugal forces are nothing but the inertia of the object.

I really wish my physics teacher explained it to me this way. I hope this helps you. Please forward the links to your friends and help them understand this better. I will keep writing articles every week.

This post was first published on June 3, 2005.


Karthikeyan KC

Aeronautical engineer, dev, science fiction author, gamer, and an explorer. I am the creator of Geekswipe. I love writing about physics, aerospace, astronomy, and python. I created Swyde. Currently working on Arclind Mindspace.

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