huntingirls02
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1) The earths gravity is pulling on you, Are you pulling on the earth Explain your reasoning with evidence.


2) Gravity is a force of attraction between objects based on their mass and their distance apart. Why aren’t other objects, like your pencil, being pulled towards you? Explain your reasoning










Gravity is a force of attraction between objects based on their mass and their distance apart. Why aren’t other objects, like your pencil, being pulled towards you? Explain your reasoning

Respuesta :

AL2006
1).  Gravity always occurs as a pair of equal forces.  I am pulling on the
Earth with a force equal to the force with which the Earth is pulling on me. 
In other words, my weight on Earth is equal to the Earth's weight on me. 
I have no observational evidence of this, but Newton tells me that it is so,
and assuming it makes Physics problems work.

Wait !  Yes, I DO have observational evidence ! 

I can turn the bathroom scale upside-down, with the stepping surface
on the floor and me standing on the floor surface of the scale.  I can also
place a tiny mirror on the floor, in which I can read the numbers.  When I
then climb onto the bottom surface of the scale, the scale is measuring the
Earth's weight on ME, and I read the number in the tiny mirror.  I recognize
it to be exactly equal to the number I read when the scale is right-side-up and
measuring MY weight on the Earth. 

Newton didn't have a bathroom scale.  But now, with better technology, we can
make measurements that he never could make, and our modern measurements
bear out his prediction.  Newton is vindicated !  Sadly, he did not live to see this.

2).  Other objects, like my pencil, as well as other people, ARE being
pulled toward me, and me toward them.  But since the Earth's mass is
about 66 thousand-billion-billion times as much as MY mass, the
gravitational force of attraction toward the Earth is somewhat more
noticeable than the force of attraction toward me.
Edufirst

These are two questions and two answers.

Question 1) The earths gravity is pulling on you, Are you pulling on the Earth Explain your reasoning with evidence.

Answer:

Yes, you are pulling on Earth.

Reasoning.

Third Newton's law of motion, action and reaction law, sates that for every action force, there is an equal (in magnitude) and opposite reaction force.

While the action force acts on one object, the reaction force acts on another the object: the object that exerts the action force feels the reaction force.

Which force is considered the action and which the reaction is totally irrelevant, they are equal in magnitude and opposite in direction.

So, consider the earths gravity's pulling on you the action force, as per Newtons's third law, you are pulling on the Earth with an equal force, which is the reaction force.

You cannot find evidence on that you are pulling the Earth due to two reasons: i) because the mass of the Earth is so big that the acceleration caused by your pulling force is neglictble, and ii) because at the same time there are so many similar forces (from the millions of people living in different parts in the planet) acting in different directions, that the net force of these forces is zero.

Nevertheless, there is another pulling force acting of the Earth which gives you evidence: it iis the attraction of the Sun. The pulling of the Sun on the Earth is what causes the almost circular orbit of the Earth around the Sun. Sun and Earth form a pair of action and reaction forces, such as you and the Earth form another pair of action reaction forces.

Question 2) Gravity is a force of attraction between objects based on their mass and their distance apart. Why aren’t other objects, like your pencil, being pulled towards you?

You exert a gravity pull on every object, including your pencil. Nevertheless, the product of your masses (yours and pencil's) is too small to show an effect.

The universal gravitational law states:

F = G m₁ m₂ / d².

Where G is the universal constant and its value is 6.67 10 ⁻¹¹ N . m²/s².

It is so small that it is only important when the masses are really big, which is not the case of yours and most object's around you. Even at very short distances the pulling forces are not important for objects that are not big like planets or stars.

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