Fictitious force

[kolahal_b]

I know there are 4 fundamental types of forces in nature.But our daily life also includes fictitious/pseudo forces. It is an unreal force, ofcourse; we need to consider it only when working from non-inertial frame. Then what will be the nature of the force as seen by an observer in a non-inertial frame?...He will observe what?maximum he may perceive something.What is the physical nature of the proposed 'something'?

[Eclogite]

But our daily life also includes fictitious/pseudo forces. It is an unreal force, ofcourse;

Would you like to give an example of such a pseudo force?

 

The intention of your post is not clear to me. Can you expand on it, or make your question/statment clearer?

[ronthepon]

The pseudo force is smoething that we merely conjure up at times to make our equations simpler.

 

An observer in a non-inertial frame will not observe this force.

 

If he does percieve something... it's merely imagination.

 

Take the centifugal force for instance.

 

It can only be felt by a person sitting on the thing that is rotating very fast. However to an outside observer, there is no such force. There is merely inertia.

[UncleAl]

Coriolis force swirls atmosphere into hurricanes and causes railroad tracks to selectively wear on one side. The Earth is not an inertial frame of reference for having angular momentum vs. the fixed stars (23h 56m 4.09074s sidereal day vs. 24h solar day.) Coriolis force is fictitious as a force, but it is real enough in effect for demonstrating inertial effects in non-inertial frames of reference.

 

If you impress a force upon a gyroscope, it precesses. If you set up a whole bunch of humongous wind generators, you likewise screw with the Earth's rotation. How much excitement can you stand?

[Tim_Lou]

actually, things are the other way around. when we experience "fictitious" force, we know that we are being accelerated and in a non-inertial system. Now what exactly is the definition of fictitious force? i think there isn't a definition, fictitious force is as "real" as the other force. we simply put some gravitional fields in our equations and apply the GR eqations (please don't ask me how, 'cause i dont even know).

[kolahal_b]

Now what exactly is the definition of fictitious force? i think there isn't a definition, fictitious force is as "real" as the other force. we simply put some gravitional fields in our equations and apply the GR eqations

I agree.But then is it either gravitational or, electromamagnetic force?

[Qfwfq]

As Tim said, Einstein's idea was that of describing the gravitational field exactly like inertial force.

 

Suppose you're sitting in a car passenger seat and the driver strongly steers left. Normally, you will say that "something" pushes you toward the right side of the car; if the car door were open and you weren't firmly seated and didn't hold on, this "force" would send you flying away from the car. This is indeed totally fictuous, utter crap, BS. The physicist will tell you instead that the car, in steering to the left, is accelerating you with it and hence applying a force to you through your butt and back and any other contact between your body and the car, otherwise you'd carry on in the same direction as before. This is a damn real force that causes you to curve with the car instead of going straight.

 

You might even say "Owch, I banged my head on the window" but, no, it was the window that banged your head cause it wasn't accelerating rightwards as much as the bodywork. The whole thing applies if the driver slams hard on the brakes. Without the seatbelt or, worse, the dashboard and windscreen, shoving you backwards you'd continue at the previous velocity instead of slowing down, along with the car.

 

If you set up a whole bunch of humongous wind generators, you likewise screw with the Earth's rotation. How much excitement can you stand?

Be serious Unk! :) Do you really think the winds wouldn't get dissipated anyway? Do you really think it makes any difference to Earth's rotation?

 

Extracting oil and gas from deep down can cause measureable subsidence in some cases. This can change Earth's moment of inertia by a slight amount with a permanent effect on the rotation. Certainly more than harnessing the wind could ever do.