[_ Old Earth _] Gravity ?

[TOG]

how about those living sideways and at other peculiar angles and centrifugal force etc - twinc

I'm not a physicist, so I can't explain it to you in detail, but I do have an elementary understanding of gravity. This will probably go over your head anyway, so the details don't matter. Any object that has mass has gravity. The more the mass, the more gravity the object has. Although it's not an exactly precise scientific explanation, you can think of gravity as a force that draws other objects to the object in question. For example, if you hold a ball at shoulder height and let go of it, the earth's gravity will pull the ball toward the earth's center.

When you have two (or more) forces acting upon the same object, what that object will do depends on which force is stronger, and on the relative directions of the forces, that is, whether the two forces are working in the same direction, in opposite directions, or at some angle in between. As long as the gravitational force is stronger than the centrifugal force, people will not go flying off into space.

The TOG​

 

[Obadiah]

I'm not a physicist, so I can't explain it to you in detail, but I do have an elementary understanding of gravity. This will probably go over your head anyway, so the details don't matter. Any object that has mass has gravity. The more the mass, the more gravity the object has. Although it's not an exactly precise scientific explanation, you can think of gravity as a force that draws other objects to the object in question. For example, if you hold a ball at shoulder height and let go of it, the earth's gravity will pull the ball toward the earth's center.

When you have two (or more) forces acting upon the same object, what that object will do depends on which force is stronger, and on the relative directions of the forces, that is, whether the two forces are working in the same direction, in opposite directions, or at some angle in between. As long as the gravitational force is stronger than the centrifugal force, people will not go flying off into space.

The TOG​

Excellent explanation that even the simplest elementary school child should be able to understand, yet explains the law of gravity perfectly!

 

[twinc]

Excellent explanation that even the simplest elementary school child should be able to understand, yet explains the law of gravity perfectly!

surely not - it must be the denser the mass not the greater the mass - twinc

I'm not a physicist, so I can't explain it to you in detail, but I do have an elementary understanding of gravity. This will probably go over your head anyway, so the details don't matter. Any object that has mass has gravity. The more the mass, the more gravity the object has. Although it's not an exactly precise scientific explanation, you can think of gravity as a force that draws other objects to the object in question. For example, if you hold a ball at shoulder height and let go of it, the earth's gravity will pull the ball toward the earth's center.

When you have two (or more) forces acting upon the same object, what that object will do depends on which force is stronger, and on the relative directions of the forces, that is, whether the two forces are working in the same direction, in opposite directions, or at some angle in between. As long as the gravitational force is stronger than the centrifugal force, people will not go flying off into space.

The TOG​

but unattached feathers do not go flying off into space - twinc

 

[TOG]

surely not - it must be the denser the mass not the greater the mass - twinc

No, it's "the greater the mass". A small, dense object has the same gravity as a large, less dense, object that has the same mass.

but unattached feathers do not go flying off into space - twinc

That's because the earth's gravity is stronger than it's centrifugal force, whether we're talking about feathers or lead weights.

The TOG​

 

[Barbarian]

how about those living sideways and at other peculiar angles and centrifugal force etc - twinc

There is no "sideways." "Down" is toward the center of the Earth. Technically, "centrifugal force" is a "fictional force" which is merely the result of two other forces.

However,the centripetal force of gravity is slightly counteracted by the inertial force caused by the velocity of the Earth rotating. But not by much, because the rotational speed of the Earth is one revolution per day. Still, it's enough to slightly distort the Earth into an oblate spheroid. But not enough that you'd notice from pictures taken from space.

Cut the string, and the ball will fly off in the path of inertia, not along the fictional "centrifugal force" path.

 

[Barbarian]

No, it's "the greater the mass". A small, dense object has the same gravity as a large, less dense, object that has the same mass.

This is true. However, since gravity is greatest at the center of the mass, a large gaseous planet will have relatively less gravity at the surface than a smaller, rocky one. For example, Uranus is much more massive than the Earth, but the gravity at the surface of the planet is about the same as it is for Earth.

 

[Barbarian]

 

[Rick W]

Here's the graphic from:
http://schools.wikia.com/wiki/Centrifugal_force

Although it is not a real force according to Newton's laws and is often refered to be fictitious, the centrifugal-force concept is a useful one, because it helps explains the sensations a rider experiences while on a roller coaster. For example, when analyzing the experience of a vertical loop, it is convenient to study the rider's sensations relative to the looping coaster rather than relative to the Earth. In order that Newton's laws be applicable in such a rotating frame of reference, an inertial force, or a fictitious force (the centrifugal force), equal and opposite to the centripetal force, must be included in the equations of motion.
To describe the fictious centrifugal force we use its potential energy. It is given by equation: