Crash Course Physics #7 Uniform Circular Motion

Ever spun around on a swing set as a kid, feeling that weird pull outwards? Or maybe you've watched a figure skater whipping around so fast they seem glued to the ice? That, my friends, is uniform circular motion in action!

Round and Round We Go!

It's not just kids and skaters. Our entire planet is in on this circular dance. We're all spinning around on Earth, and Earth is spinning around the sun! Talk about a never-ending ride.

What makes this "uniform" circular motion so special? Well, it's moving at a consistent speed in a circle. The speed stays the same, but the direction? That's a whole different story.

The Direction Dilemma

Imagine driving a car. If you're going straight, your direction is obvious. Now, imagine driving around a roundabout. Even if your speedometer is constant, are you still going straight?

Nope! You're constantly changing direction. And that change in direction? That's acceleration! Even though you're not speeding up or slowing down. Mind. Blown.

This acceleration has a fancy name: centripetal acceleration. It always points towards the center of the circle.

Forcefully Drawn Inward

So, what causes this inward pull? That’s centripetal force. This is the force that keeps an object moving in a circle. Think about that skater again.

The ice exerts a force on their skates, pushing them towards the center of their spin. Without that force, they wouldn't stay in that beautiful circle; they'd just go flying off in a straight line!

Even the Earth going around the Sun, that’s not magic, its gravity providing the centripetal force!

The Myth of Centrifugal Force

Now, here's where things get a little tricky, there’s no such thing as centrifugal force! Many people feel like they are being pushed outwards, but what you’re feeling is inertia, your body’s tendency to keep moving in a straight line.

When you are in a turning car, the door slams into you. It's not a force pushing you against the door; it's the door changing your direction! You naturally wants to go straight, while the car makes a turn!

Swinging into Understanding

Going back to the swing set, the chains pull you inward, towards the center. That's the centripetal force at work. Your inertia? That’s the feeling that you are being pulled outwards!

The faster you swing, the more force the chains have to exert to keep you in that circular path. That's why swinging higher feels more intense!

So, the next time you're on a carousel, or watching a race car zoom around a track, remember uniform circular motion. It's a constant battle between inertia and the inward pull, and it's happening all around us!