Why is Centrifugal force “not real”? I remember my physics teacher in high school pushing that idea and understanding why back then, but I do not remember now. I also forgot so much about physics in general that a simple would be much appreciated!
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It’s a fictitious force, so it’s only used in a non intertial reference frame. Now what does that mean?
A non intertial reference frame means that the frame of reference you are measuring the motion against, is accelerating.
An example of an intertial reference frame would be what you do in conventional physics. The ground is stationary, and if you throw a ball, it acts exactly as you’d expect.
Another example of an inertial reference frame would be a car moving at a constant velocity. You throw the ball and it travels exactly the same as before.
Once you start accelerating the car, the reference frame becomes non inertials. Let’s say the car is accelerating at “a”. If you throw the ball now, it will appear to be accelerating the opposite direction of the car, so to be in the reference frame of the car, we need to add a fictitious force acting on the ball such that F=ma, m being the mass of the ball, a being the acceleration of the car. When you get pressed back into the seat of the accelerating car, or get thrown forward by a fast stop, that’s the same fictitious force.
The centrifugal force is for a rotating reference frame. Since the centripetal force is constantly accelerating everything in the rotating body towards the center, if we want to be in the reference frame of the rotating body we need a ficticious force acting outward on everything in the system. We call this force the centrifugal force and it will have an equal magnitude and opposite direction of the centripetal force that would allow the object to travel in circular motion.
Another fictitious force for rotating reference frames is the coriolis force, you may have heard of the coriolis effect, the coriolis force is how we explain it while keeping the Earth as the reference frame. This one only applies when the object in the reference frame moves towards or away from the axis of rotation.
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