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!
In: 6209
Additional question. It’s one of those funny words that gets said in multiple ways around the English speaking world. So I’m kinda curious which people here say (and your accent)?
– sentry few jal (heard a lot)
– sentry few gal (also heard a lot)
– cent riff e cal (my dad with a York accent says this in a super specific way lol sennnntrifical)
Personally I can never decide, I hear all 3 in Australia.
Centrifugal force is “not real” because pretentious assholes like to pretend they’re very smart. Just ask them what the equal and opposite force to the centripetal force is, and what they would call it.
As an example, if you are in a car making a sharp turn, you feel like you are being pushed into the side of the car. But what is happening is that your inertia resists the change in direction, and the side of the car is pushing on your body to cause it to accelerate in the direction of the turn. This feels to you just like a gravitational force pushing you away from the center of the turn (and Albert Einstein says they’re indistinguishable).
But because baby physicists only do inertial reference frames and never accelerating reference frames, they can’t use the perspective of what it looks like to you. In any case, they get so caught up explaining, that they forget that the whole thing was originally called the centrifugal force.
**In summary, inertia is what keeps your body moving straight such that side of the car pushes into you, centripetal force is what accelerates your body into following the curve, and centrifugal force is the force your body exerts on the car.**
[removed]
Centrifugal force is “not real” because pretentious assholes like to pretend they’re very smart. Just ask them what the equal and opposite force to the centripetal force is, and what they would call it.
As an example, if you are in a car making a sharp turn, you feel like you are being pushed into the side of the car. But what is happening is that your inertia resists the change in direction, and the side of the car is pushing on your body to cause it to accelerate in the direction of the turn. This feels to you just like a gravitational force pushing you away from the center of the turn (and Albert Einstein says they’re indistinguishable).
But because baby physicists only do inertial reference frames and never accelerating reference frames, they can’t use the perspective of what it looks like to you. In any case, they get so caught up explaining, that they forget that the whole thing was originally called the centrifugal force.
**In summary, inertia is what keeps your body moving straight such that side of the car pushes into you, centripetal force is what accelerates your body into following the curve, and centrifugal force is the force your body exerts on the car.**
Centrifugal force absolutely *is* real. It’s just fictitious, because it’s not real *in an inertial reference frame*.
Let me ELI5: let’s say you, a 5-year-old, hold on to a rope, and I swing that rope around and spin you. (I think I can still do that to my 5-year-old, but she’s getting a bit too big now. Anyway.) What will that feel like *to you*? You’ll want to hold on tight, because if you let go, you’ll *shoot* off. That’s a force pushing you *away* from the center — centrifugal. What will that feel like to *me*? Well, I’m spinning you, so I’m actually pulling you towards me at the center — I’m exerting a centripetal force. When you’re spinning, what you actually want to do is travel in a straight line, so I have to pull you into me so that you turn around the circle instead.
For me, I’m standing still in a frame that’s moving at constant velocity — in this case, velocity 0 relative to the ground — and I’m *exerting*, with my arms, a centripetal force to pull you in and keep you from traveling in a straight line. You are moving around in a circle, so what you feel is a force pushing you *out* of the circle, and if you let go, you’ll go flying off out of the circle (which to me looks like you traveling in a straight line).
If we think only about frames of reference moving at constant velocity — what we call inertial frames — then there is no centrifugal force; it’s fictitious. But when we talk about frames that are *not* moving at constant velocity, like frames going around in circles or otherwise accelerating, you *do* feel a centrifugal force. You do actually feel it; it’s real to you. But what you’re really feeling is the acceleration of the frame itself. We call it a fictitious force because it doesn’t exist in an inertial frame. Other fictitious forces are the Coriolis force (which pushes you in fairly weird ways), the azimuthal force (has to do with acceleration of rotation, very complicated), and the good ol’ linear acceleration force, which is the force that pushes you forward into your seatbelt when your mommy brakes the car really hard. These are all forces that you feel not because something is applying that force on you but because of how you’re moving.
[removed]
Centrifugal force absolutely *is* real. It’s just fictitious, because it’s not real *in an inertial reference frame*.
Let me ELI5: let’s say you, a 5-year-old, hold on to a rope, and I swing that rope around and spin you. (I think I can still do that to my 5-year-old, but she’s getting a bit too big now. Anyway.) What will that feel like *to you*? You’ll want to hold on tight, because if you let go, you’ll *shoot* off. That’s a force pushing you *away* from the center — centrifugal. What will that feel like to *me*? Well, I’m spinning you, so I’m actually pulling you towards me at the center — I’m exerting a centripetal force. When you’re spinning, what you actually want to do is travel in a straight line, so I have to pull you into me so that you turn around the circle instead.
For me, I’m standing still in a frame that’s moving at constant velocity — in this case, velocity 0 relative to the ground — and I’m *exerting*, with my arms, a centripetal force to pull you in and keep you from traveling in a straight line. You are moving around in a circle, so what you feel is a force pushing you *out* of the circle, and if you let go, you’ll go flying off out of the circle (which to me looks like you traveling in a straight line).
If we think only about frames of reference moving at constant velocity — what we call inertial frames — then there is no centrifugal force; it’s fictitious. But when we talk about frames that are *not* moving at constant velocity, like frames going around in circles or otherwise accelerating, you *do* feel a centrifugal force. You do actually feel it; it’s real to you. But what you’re really feeling is the acceleration of the frame itself. We call it a fictitious force because it doesn’t exist in an inertial frame. Other fictitious forces are the Coriolis force (which pushes you in fairly weird ways), the azimuthal force (has to do with acceleration of rotation, very complicated), and the good ol’ linear acceleration force, which is the force that pushes you forward into your seatbelt when your mommy brakes the car really hard. These are all forces that you feel not because something is applying that force on you but because of how you’re moving.
[removed]
Centrifugal force absolutely *is* real. It’s just fictitious, because it’s not real *in an inertial reference frame*.
Let me ELI5: let’s say you, a 5-year-old, hold on to a rope, and I swing that rope around and spin you. (I think I can still do that to my 5-year-old, but she’s getting a bit too big now. Anyway.) What will that feel like *to you*? You’ll want to hold on tight, because if you let go, you’ll *shoot* off. That’s a force pushing you *away* from the center — centrifugal. What will that feel like to *me*? Well, I’m spinning you, so I’m actually pulling you towards me at the center — I’m exerting a centripetal force. When you’re spinning, what you actually want to do is travel in a straight line, so I have to pull you into me so that you turn around the circle instead.
For me, I’m standing still in a frame that’s moving at constant velocity — in this case, velocity 0 relative to the ground — and I’m *exerting*, with my arms, a centripetal force to pull you in and keep you from traveling in a straight line. You are moving around in a circle, so what you feel is a force pushing you *out* of the circle, and if you let go, you’ll go flying off out of the circle (which to me looks like you traveling in a straight line).
If we think only about frames of reference moving at constant velocity — what we call inertial frames — then there is no centrifugal force; it’s fictitious. But when we talk about frames that are *not* moving at constant velocity, like frames going around in circles or otherwise accelerating, you *do* feel a centrifugal force. You do actually feel it; it’s real to you. But what you’re really feeling is the acceleration of the frame itself. We call it a fictitious force because it doesn’t exist in an inertial frame. Other fictitious forces are the Coriolis force (which pushes you in fairly weird ways), the azimuthal force (has to do with acceleration of rotation, very complicated), and the good ol’ linear acceleration force, which is the force that pushes you forward into your seatbelt when your mommy brakes the car really hard. These are all forces that you feel not because something is applying that force on you but because of how you’re moving.
You are sitting at a stop light. Dom Toretto pulls up next to you and starts revving. You are ready to throw down as well since you also live your life one quarter mile at a time.
The light turns green, you floor the gas. You are instantly pushed into your seat. But now think about the forces. The engine and wheels are providing a force forwards and the car is forcing you forward as you do 0 to 60. But you **feel** like you are being pushed backwards.
There is no real force pushing you into your seat; the real force is the car propelling you forward trying to catch Dom as all you see are his taillights. But it feels like someone is crushing you into your chair.
Latest Answers