what is centrifugal force?



what is centrifugal force?

In: Physics

The outward force of something spinning. Think of a salad spinner, by spinning the bowl really fast, the water on the leaves gets thrown outward.

Hope this helps, if not, I’m sure someone else can explain better.

Newton’s 1st law
In an inertial frame of reference, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force.

So making something spin in a circle requires force to change the object’s path. That is why centrifugal force can mimic gravity, like G forces in fighter planes.

Centrifugal force is the term for the combine actions of inertia and centripetal force. Centripetal force is a force that acts on a body moving in a circular path and is directed toward the center around which the body is moving. Inertia is a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.

Using a ball on a string for example.

You start spinning the ball around your head. Centripetal force is caused by the string pulling the ball in, while inertia is trying to keep the ball moving in a straight line away from you.

It’s a mistaken idea.

While it’s common to see forces from the observer’s point of view, that’s often wrong. Most physics tries to avoid non-inertial reference frames.

So everything that is moving in a certain direction will want to keep moving in that direction, this is called momentum.

If you attach a ball to the end of a rope and start swinging it around in a circle, the ball will experience a centrifugal force. At any moment, the ball wants to head straight, because it has momentum, but the rope stops it from doing this. So there is a force here: we need the rope to overcome the ball’s momentum and pull it into the circular path.

This may seem a bit abstract so here’s an analogy:

Imagine you’re in a bus, and the bus goes around a corner. Let’s say the bus is turning left. You will feel like you’re being pushed to the right side of the bus. This is because the wheels on the bus tell the bus to go left, and because the bus is attached to the wheels it turns left. You are not fastened to the bus so your body wants to keep going in the direction it was going (momentum) because nothing has forced your body to change direction. This is the reason you are pushed to the right side of the bus: your body wants to keep going straight but the bus is turning left.

Now imagine the bus is turning left and then immediately turns left again (a U turn). Your body wants to go straight so the first left causes a force that turns your body in the same direction as the bus. Then the moment your body has also made the turn and is about to start going in a straight line again (and the force pushing you to the right side of the bus disappears) the bus turns left again, restarting the process.

Now imagine the bus is going around an endless corner. Endless corners are conveniently called circles. Every moment your body wants to go in a straight line but the bus forces it to change its path. You would feel a continuous force. This force is the centrifugal force.

It’s important to realise that the centrifugal force *does not point directly outwards*. It points in the direction the object would go if someone cuts the rope keeping it in a circular path. In the bus the force keeping it in a circular path is the friction between the tyres of the bus and the road. In the ball on a rope analogy it’s the rope.

I hope this answers your question!

I actually made a video to answer this exact question:


The general idea is that the centrifugal force shows up when you are standing in a reference frame that is spinning in a circle. It’s very analogous to the downward force you feel when an elevator is accelerating upwards. Gravity doesn’t actually get stronger, but to you, it feels like there is more force pulling you into the floor. If your reference frame is spinning, it has to be constantly undergoing acceleration towards the center of the circle. Just like the elevator, you feel an extra force that is opposite to the direction of acceleration, making you feel like you are being pushed out of the circle. That is the centrifugal force.

It’s the push required to keep your path moving in a circle when it wants to go straight.

Sometimes called a fictional force because it feels like you are being thrown to the outside of the circle which isn’t quite the same thing.

Imagine a golf ball inside a glass. The ball likes that glass. Normally, the ball falls out of the glass when it is tipped upside down. However, when spinning, the ball gets scared and clings to the glass. It does not fall out of the glass.