What's The Difference Between Centrifugal And Centripetal Forces?

When humanity first started studying motion, circles posed a peculiar puzzle. Why do planets sweep endlessly around the Sun without flying off into the void of space? Why does a stone swung on a string trace a perfect arc instead of darting straight away? These questions were asked even before the age of space travel by great minds such as Copernicus, Galileo, and Kepler. However, it was Isaac Newton who gave circular motion its mathematical form.

In the 17th century, Newton's Principia introduced the laws of motion and gravitation, offering a framework to explain not only the paths of the planets, but also the tug and pull felt by the spinning objects. Alongside these laws emerged the concepts of centripetal and centrifugal forces. Since then, these two terms sparked debate, confusion, and fascination in equal measure. They're still main concepts in the physics classrooms, but they also shape our understanding of motion in day-to-day life. So what's really the difference between centrifugal and centripetal forces, and how to tell them apart?

If you try to swing a bucket full of water in a vertical circle, the water won't spill. The answer lies within two natural forces that often get mixed up: centripetal and centrifugal. Centripetal force (from Latin centrum, meaning center, and petere, meaning to seek) is the real physical force that keeps an object moving in a curved path. It always points inward, towards the center of the circle. In the bucket example we just used, the handle keeps the bucket swinging around the center instead of allowing it to fly off in a straight line. It's this inward pull that's the centripetal force.

Centrifugal force (from centrum, meaning center, and fugere, meaning to flee) feels the opposite of centripetal force. But centrifugal is not the real force in the Newtonian sense. It's what we call a fictitious or apparent force that pushes the spinning objects outside. Imagine yourself in a fast-rotation carousel. It feels as if you're being pushed outwards, against your seat. In reality, your body just wants to continue flying in a straight line, but with the carousel seat spinning under you, keeping you in place. That push you feel is centrifugal force. This force shows up only when you're within the rotation reference frame. It's your perspective from inside the carousel that makes you feel as if you're being pushed away. There's no real force at play.

So, the difference between these two forces is this: centripetal force is real and inward, while centrifugal force is apparent and outward. One keeps objects moving in the circle, while the other explains the sensation of being spun when you're in the circular motion yourself. In short, centripetal force acts, while centrifugal force is what we feel. Although both terms matter, only one is a true physical force.

It's easy to see why centripetal and centrifugal forces are often confused. Our senses tell us one story, while physics tells a different one. If you're riding on a carousel, from the observers outside, it's clear that the ride's construction provides the inward pull. For you, inside the ride, it feels as if something is tugging you outward, trying to slide you off the seat. What you feel is centrifugal force, a byproduct of your body's inertia as it resists the constant change in direction.

It's this clash between what we feel and what physics and mathematics explain that makes the confusion about centripetal and centrifugal forces persist. The centrifugal force is so convincing that it feels real. Our senses interpret inertia as an outward shove. It's an illusion that makes sense only if you're inside the rotating system. Even astronauts, well aware that it's not a real force, cannot shake the feeling of outward pressure during the centrifuge training. However, the confusion is also perpetuated by the similar-sounding names for the two forces and centuries of loose usage. They both describe the same circular motion, but from a different point of view. It's no wonder the lines between the two concepts are so blurred.