Centrifugal force due to rotation of Earth

[Humberto]

I was wondering why we appear not to feel any centrifugal force due to the rotation of Earth, the revolution of Earth around the Sun, or the revolution of the Solar System around the Milky Way, etc.

It turns out the centrifugal force at the equator due to Earth's rotation is 1/289 standard gravity, see http://en.wikipedia.org/wiki/Centrifugal_force_(rotating_reference_frame)#Earth.

 

[DJ...]

So you asked and answered your own question...:erm:

 

[koeksGHT]

So you asked and answered your own question...:erm:

And makes a thread about it

No one getting dizzy from earth rotation? Haha

 

[Humberto]

I think the reason why one doesn't feel centrifugal force caused by the rotation of Earth isn't because of its small magnitude, but because the force is directed opposite to gravity. It cancels out a portion of the force caused by gravity. I was under the impression that the force would be directed diagonally upwards, but it seems it isn't. It is directed straight up.

As I understand it, 1/289 standard gravity corresponds to a force of 0.034 N.

 

[sanimoyo]

There is a ride at Gold Reef that I am sure uses the centrifugal force.

 

[kripstoe]

So would you feel the effect of centrifugal force if there was no gravity and you were not tied to the planet somehow?

 

[Moosedrool]

There is a ride at Gold Reef that I am sure uses the centrifugal force.

I hate the term centrifugal force when dealing with theme park rides.

It's simply called acceleration in engineering regardless of whether it's changing velocity or changing direction. All is acceleration aka force required to change its velocity along a straight axis. Changing direction relative to this axis means the velocity relative to that access will also change. The speed relative to the object remains the same. All roller coaster and moving theme park rides exerts forces.

On a roller coaster train, car or plane etc... you can split the resultant force up into vectors for all three dimensions known as lateral G's, Vertical G's and longitudinal G's. Gravity always gets calculated in for anything built on earth and will always exert 1 G down thus for a coaster to create weightlessness you need a parabolic shaped curve (camel back) that will produce the exact opposite. At the crest the G's will be Ver = (+1, -1) = 0, Lat = 0, Lon = 0.

 

[Humberto]

So would you feel the effect of centrifugal force if there was no gravity and you were not tied to the planet somehow?

If everything stayed the same except your own body became impervious to Earth's gravity, you'd tend to gradually float up in the air if you weren't careful.

 

[Moosedrool]

So would you feel the effect of centrifugal force if there was no gravity and you were not tied to the planet somehow?

If everything stayed the same except your own body became impervious to Earth's gravity, you'd tend to gradually float up in the air if you weren't careful.

Yes, you'll repeatedly have to grab no too whatever is attached to the earth in order to remain on it. Basically if gravitational force cease to exist all the objects on earth will just go in straight lines off into space as the earth turns. For you it will seem like you're being pulled off the ground.

 

[bhekisisa]

it is true that positive plus negative =0. so centrifigal force its hard to affect us due to gravitational force. but why do we experiance earth shaken?

 

[DJ...]

it is true that positive plus negative =0.

Not necessarily. 2 + (-1) = 1. Coincidentally this is the reason you feel the earth shake too, as one force is not balanced equally by another external force. In other words, one force exceeds another. There are other factors involved here too such as the direction of the force, but in simplistic terms this is why we can feel the earth shake - because positive plus negative does not always equal zero. And because sometimes both forces act in the same direction too...

 

[grok]

Reminds me of this oldie ..

Gravity is a myth .. the earth sucks!

 

[Swa]

Space elevators

 

[dabbler]

Does this mean that you weigh less at the equator compared to what you weigh when you are at the North or South pole?

 

[Humberto]

Though if you use the same scale it will read 100kg at both the pole and the equator since the centrifugal force also acts on it.

Dunno about this.

 

[BigAl-sa]

Your mass will never change, but you will weigh about 300g less at the equator if you are 100kg at the poles. Though if you use the same scale it will read 100kg at both the pole and the equator since the centrifugal force also acts on it. However, the loss in 300g of weight at the equator will allow you to jump slightly higher at the equator than at the poles.

?
Be careful about using mass and weight in the same sentence. You are referring to measuring devices...

 

[Humberto]

Regarding the same reading on the bathroom scale, think about the forces involved and how the measurement of your mass is calculated by the scale.

I think a balance scale would give you the same weight reading but I think a spring scale wouldn't. The net gravity-centrifugal force at the equator is less than at the poles and this would cause the spring in a bathroom scale to compress less when standing on the scale, but I don't think the spring's resistance to compression would differ between the equator and the poles.

 

[louisek]

Galileo tried to answer this question in 1608 but got it all wrong. He also thought comets were reflections of the sun from objects in the atmosphere

 

[Humberto]

Another factor that influences your weight on Earth is your altitude as this determines the distance to Earth's center of gravity.

Earth is not spherical but an oblate spheroid so that it's diameter at the equator is 43 km greater than at the poles. This further reduces the force of gravity at the equator.

Here is a list of the force of gravity at different cities around the world:

http://en.wikipedia.org/wiki/Gravity_of_Earth#Comparative_gravities_in_various_cities_around_the_world

 

[BigAl-sa]

Why the confusion? I thought I clearly pointed that the mass won't change but the weight will.

Regarding the same reading on the bathroom scale, think about the forces involved and how the measurement of your mass is calculated by the scale.

Again, you're looking at measuring devices. A bathroom scale measures weight not mass, it does not calculate anything.