Why is centrifugal force considered fictitious, when it's the one that feels real to us when we are moving in a circle? I understand the explanation regarding the reference frames: if our body is the reference frame, and it is rotating, a fictitious centrifugal force needs to be made up to cancel the centripetal force and explain why we appear to be stationary in relation to ourselves. However, if we are in a round up ride, we feel pushed againsts the wall, rather than towards the center of the ride, which would be the centripetal force. So if centrifugal force is the fictitious one, wouldn't that be like saying that the force we feel pushing us againsts the wall is only in our minds?
Centrifugal Force – Why Is Centrifugal Force Considered Fictitious While It Feels Real to Us in Circular Motion?
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Firstly, it is important to know that centifugal force is not a real force, it is only an apparant force. The centrfugal force is really just how a rotating object feels the centripetal force.
Imagine you are on one of those spin-rides like the Gravitron where you sit up against the wall as it spins. You will feel a centrifugal force, but an observer from the outside will only see the centripetal force.
Newtons first law (aka law of inertia) says an object in motion wants to stay in that motion. At any instance on the ride, you are moving in a straight line tangential to the circular path. But the walls then provide the centripetal force that pushes you back in. So what you are feeling is your body literally running into a wall via your linear velocity. If the wall pushes on you, newtons third law says you will feel yourself push on the wall.
Now back to the string and ball example, we can see that the centrifugal force is actually just a product of newtons third law of motion - every action has an opposite and equal reaction. While the ball is in motion, your hand has to provide a force(in this case the centripetal force) on the string to keep the ball in its circular path. Consequently, the string must then pull on your hand equally and oppositely. That is the centrifugal force your hand feels. As for the ball, it keeps trying to go linearly but gets pulled in. If you yourself replaced the ball and was spun about, your body would want to keep moving in a straight line (bc of its inertia) but you kept being pulled inwardly instead. As you are spun, the rope pulls on you and so you must then pull on the rope. Thus, it will feel like your body is trying to fly outward.
The moment you let go, the centripetal foce and its apparent centifugal force is gone and the ball continues moving in the direction of its linear velocity at that moment.
You do not feel the centrifugal force. What you feel is the centripetal force (which is the contract/friction force that your seat in your car applies to you) pushing you inward.
Try the following Gedankenexperiment: Imagine your car was not turning, but only being accelerated sideways in a straight line. In which direction would the car have to accelerate, to give you the same feeling you have when turning. In which direction is the force on your car going? You will see, that it's the inwards force that you feel when turning, preventing you from following a straight line.
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Suppose you're in a fast car and you stomp on the accelerator. You feel pressed into the back of the seat. In which direction are you accelerating? Forward, obviously, but you feel a force pushing against your back. Now you turn a corner. Your seatbelt, and maybe the door next to you, press against your side. In which direction are you accelerating? In this case, it's not so obvious, but it's inward, not outward. There is no centrifugal force here.
In both cases, the side on which you feel the force is opposite the direction in which you are accelerating.