What is the force that pulls a person toward the center of the earth?

Question

It has to be either A. The person's gravitational force or B. the Earth's gravitational force

Answer 1

The best answer to the question as set is "It's BOTH, because the force of gravity is a MUTUAL FORCE." But I consider the question itself seriously flawed, as its either/or stipulation presents a false and incomplete scientific choice.

Both FORCES are absolutely EQUAL (but opposite) to one another, so that the division into " A. The person's gravitational force or B. the Earth's gravitational force " is technically MEANINGLESS from the point of view of FORCE alone. This MUTUAL FORCE simply cannot be separated into "the person's gravitational force" and "the Earth's gravitational force."

However, because a person's mass is so much LESS than the Earth's mass, the person's ACCELERATION induced by this MUTUAL FORCE is that much greater than the Earth's acceleration, in the ratio of M_Earth / m_person. That's one HELL of a HUGE FACTOR!

So, to all intents and purposes we can say that the person is the object doing the moving and accelerating, while the Earth is effectively stationary, and also that the acceleration [has anyone even bothered to read that?! --- the ACCELERATION] of the person is due to the Earth pulling on him/her.

Thus, if you're not using the scientific term FORCE, it's perfectly O.K. to say that the person is "pulled toward the Earth by the Earth's attraction." That's a fuzzy way of describing the end result of the person having essentially all the acceleration.

Nevertheless, and to repeat the essential point yet again, at a more FUNDAMENTAL level one should NEVER lose sight of the fact that the GRAVITATIONAL FORCE is MUTUAL. Its EFFECTS on each of the two masses involved, however, are simply and necessarily INVERSELY PROPORTIONAL to the mass of each one of that pair of masses.

Live long and prosper.

LATER ADDITION: You're almost ALL missing the point that the question asked about which FORCE was responsible. The scientific answer is THEIR MUTUAL GRAVITATIONAL FORCE, and NOT "A, the person's gravitational force," or "B, the Earth's gravitational force."

I would agree (if the point were made) that the questioner probably wasn't too clear in his/her own mind that the use of the word force has definite technical scientific implications that the fuzzy word "attraction" doesn't. Nevertheless, it DOES have such a definite scientific meaning, and it's no good ignoring that and substituting fuzzier concepts that have the observed accelerations, rather than the mutual force, underlying them.

There is no such thing, in complete isolation, as ONE MASS'S GRAVITATIONAL FORCE. It's a MUTUAL thing, like having a baby. It takes two to tango, and two masses to produce a gravitational force. JHEEZ! You all should know that. Where on Earth were you taught?

You have all allowed yourselves to be (il)logically MESMERIZED by the INDUCED ACCELERATIONS, which are simple CONSEQUENCES of the mutual force, but are NOT those forces per se.

You're interpreting the DOMINANT ACCELERATION as a DOMINANT FORCE, but FORCE and ACCELERATION have DIFFERENT DIMENSIONS. They're NOT the same!

If you were in one of my classes, you'd all FLUNK for failing to appreciate the difference between a mutual force, and the very different accelerations it induces.

Answer 2

The Earths gravity pulls the person toward the Earth. The answer is NOT both because the person's gravity pulls the earth towards the person.

Dr Spock makes a good point in reminding that Gravity forces effect both objects, but the question is worded in such a way that is not asking which objects are affected by gravity, but rather which objects gravitational force is greater than the other, and therefore what is doing the pulling.... Gravitational forces can only attract objects, so it cannot be said that the gravititaional force of the person is PULLING the PERSON to the center of the earth - that is clearly untrue - its the gravity of the Earth pulling the person to the Earth.

Answer 3

The person’s gravitational force is acting on the earth. Therefore it cannot pull him down.

The earth’s gravitational force is acting on the person. Therefore it pulls him toward the center of earth.

If one force is action, then the other force is reaction. Action and reaction forces do not act on one and the same object.

The motion of the object is determined by the net force acting on the body and not by the forces acting on different bodies.

When gravitational force pulls an object, it is accelerated and it is in accelerated motion. If any other external force ( for example the reaction of the ground) nullifies this gravitational pull, then the object comes to rest or in uniform motion.

Answer 4

The gravitational force of a person compared to the earth is not even measurable. Think about it... Gravity is caused by the relationship of large bodies. Like moons, planets, etc... Good question.

Answer 5

B. the earth's gravitational force.

Answer 6

If we are looking for the best answer it is B.
F_g = G*M*m/r/r where G is the gravitational constant, M is mass of large body, m is smaller mass, r is distance from center to center of the masses.
In theory this means that earth pulls the person towards its center and at the same time, the person pulls earth towards itself, although by so small a magnitude that it is not noticeable. But what we are being asked is: what pulls the person towards the earth? It is B ONLY.
Say the average person is about 90 kg,
F_g due to person = Mg = GMm/r/r
g of earth, due to person = Gm/r/r
= 6.7 x 10^-10 * 90 kg / (6.3 x 10^6)^2
= 1.5 x 10^-21 m/s/s
So the earth "accelerates" towards the average person at a rate about one billionth of a billionth of a ten-thousandth that a person accelerates towards earth!

Answer 7

b) the earth's gravitational force

Answer 8

Both...if an object has mass, it has some gravitational pull. A person does not have much pull, but it is there because they have mass.

Answer 9

Hypothetically speaking, definite. yet purely after a super variety of rocking around the centre. you may shoot previous the centre using your momentum from the fall, and attain very just about an identical height you have been at earlier falling in, yet then gravity could take over and you will fall backtrack back. After each fall, you will lose some momentum, until you're caught on the centre of the planet.

Answer 10

Earth's force.