Gravitational force Definition and 491 Threads

I ordinarily would put this up in a homework/ coursework forum, but this isn't either one, its just something I was curious about given that I am in a Mechanics class. So, I have done calculations for finding the gravitational force from a sphere and from a ring, and a flat circular plate. All...

Homework Statement 1) A 0.25kg book rest on a table. A downward force of 9.5 N is exerted on the top of the book by a hand pushing down on the book. 2)what is the size of the normal force exerted by the table on the book Homework Equations F=ma The Attempt at a Solution 1)...

In my book it is written that Newton's shell theorem can be used to show that a uniform shell of matter exerts no net gravitational force on a particle located inside it. How?

I had this doubt right from my school days. What is actually gravity? what causes it? is that the core of a planet or any other forces? What creates the gravitational forces.?

We know Moon creates tides on seas.Then why doesn't Moon pull loose stones or other objects lying loose on earth?

Homework Statement At what distance r inside the Earth is the gravitational force due to Earth the same as at the distance r = 4RE (where the latter distance is clearly outside Earth)? Assume uniform density of Earth. Homework Equations conservation of energy? TME = GPE + KE...

I would like to know how it is possible that I can be at rest on the surface of the Earth (relative the the Earth of course). My main cause for confusion is the action reaction pair that occurs when I stand on the surface of any solid material. The normal reaction nornal reaction a-r pair...

has anyone tried to merge gravity and the strong force mathematically? The two seem very compatible--the gloun is the only vector boson capable of causing a force to be applied between two similarly charged objects. Isn't it likely that there is some kind of gluonic field, which behaves...

Homework Statement In a particular binary star system, Star A has a mass that is 28 times that of Star B. This distance between the stars is 34 AU (astronomical units). Find the location of the point in this star system where the net gravitational force on any mass would be zero. Homework...

1. Homework Statement A 450 kg satellite orbits at a distance from the Earth's center of about 6.5 Earth radii. What gravitational force does the Earth exert on the satellite? 2. Homework Equations Gravitational force= G* ((mMe)/(r^2)) 3. The Attempt at a Solution G times mass...

Homework Statement Some of the earliest atomic models held that the orbital velocity of an electron in an atom could be correlated with the radius of the atom. If the radius of the hydrogen atom is 10^−10 m and the electrostatic force is responsible for the circular motion of the electron...

Hello guys! According to relativity, objects with higher kinetic energy have larger mass. Would that affect the gravitational force of the object? Or in other words, if a neutron moves faster, would it attract other things more strongly? tyvm

I posted this in the intro section and realized the answer might be more difficult than anticipated, sorry I won't double post anymore X_x 1. Homework Statement The effect of gravity on a point mass is given as F(r), where r is the radius between the point mass and the Earth's center. If you...

Homework Statement The effect of gravity on a point mass is given as F(r), where r is the radius between the point mass and the Earth's center. If you could place the point mass at R/2, where R is the radius of the earth, what would the relationship be between F(R)/F(R/2)Homework Equations Fg =...

Homework Statement (a) Compute the vector gravitational field at a point P on the perpendicular bisector of the line joining two objects of equal mass separated by a distance 2a as shown in Figure P13.26. (b) Explain physically why the field should approach zero as r ---> 0. (c) Prove...

Hi, I'm wondering if anybody could explain me the difference between these two concepts with a clear definition for someone who JUST began physics. Thanks ! Particularly, concerning this equation w=Fg=mg Also, just to be sure I'm doing it in the right way, could I say that would be good...

gravitational force act in pairs, and they act toward the center of the earth. does it mean that if u find yourself at the Earth center will your fill weightless?

It has occurred to me that gravitational force on an object will change as the object falls toward the Earth. I modified Newton's equation F=GMm/(r^2) to reflect the change in force over time: F = GMm/[r-.5a(t^2)]^2 Now that I have the equation I'm trying to figure out the instantaneous change...

I have physics homework and came across this question : I was asked to find the electrostatic force between two charged particles each having a charge of +5.0x10-9 C and which were separated by a distance of 3cm. I found it to be 2.5x10-4 N.Then I was told to calculate the gravitational force...

This is a really dumb question but I can't seem to make sense out of this... For a conservative force, we have \vec{F}=-\nabla \phi, where \phi stands for the potential. So let's take the gravitational potential, given by: \phi=-G_N \frac{M}{r}. Then, by the previous formula: \vec{F_g}=-G_N...

Hello everyone, We regard a satellite with only the gravitational force working on it. My textbook states that the net force in the x-direction is: -Fgrav*(x/r), with r being the distance between the satellite and the Earth. Could anybody explain this to me? Thanks in advance, Tom Koolen

I just have a question concerning a previous thread about gravitation. The formula is from post 19 at https://www.physicsforums.com/showthread.php?t=635188&page=2 v= dr/dt a = dv/dt multiply by dv/dt by dr/dr: a = (dr dv)/(dt dr) = v dv/dr This gets you to the first step...

Homework Statement This is question 3.7 from Gregory's Classical Mechanics textbook. A symmetric sphere of radius a and mass M has its center a distance b from an infinite plane containing a uniform distribution of mass ## \sigma ## per unit area. Find the gravitational force exerted on the...

Energy gravitates. Is is so simple as to replace M in gravitational euqations with E/c*c ? F=\frac{G*M\underline{1}*M\underline{2}}{DM\underline{1,2}}=F=\frac{G*E\underline{1}*E\underline{2}}{c\overline{4}*DM\underline{1,2}}

Homework Statement The similarity of form of Newton’s law of gravitation and Coulomb’s Law caused some to speculate that the force of gravity is related to the electrostatic force. Suppose that gravitation is entirely electrical in nature—that an excess charge Q on the Moon and an equal and...

Homework Statement A particle is to be placed, in turn, outside four objects, each of mass m: (1) a large uniform solid sphere, (2) a large uniform spherical shell, (3) a small uniform solid sphere, and (4) a small uniform shell. In each situation, the distance between the particle and the...

In order for a satelite to achieve an orbit around the Earth the centripetal force of it needs to be exactly the same as the force of gravitation which is acting upon the satelite. Why is this so?

How was this formula derived? Gravitational stuff... This is embarrassing but I need to understand it. I'm trying to understand how to solve a problem but I don't understand how one of the variables was isolated for and I was hoping someone here could explain it please. It's seemingly basic...

I just watched the first 10 minutes of a documentary that seemed to touch on Walter Crutenberg's premise of our Sun being a binary twin of Sirius. Sirius A and B are separated by (at most) ~31 AU (1 AU = distance from Earth to Sun, 149,598,500 km). The Sirius system is 8.6 ly from Earth...

I am reading Kolenkow and Kleppner's Classical Mechanics and they have tried to calculate the gravitational force between a uniform thin spherical shell of mass M and a particle of mass m located at a distance r from the center. The shell has been divided into narrow rings.R has been...

I've been wondering.. If a person (A) is, say, on top of Mt. Everest, he would be moving faster than a guy (B) at the foot of the mountain since A is further from the center of the earth, but he would also be experiencing a weaker gravitational force than B. So, for which of the invidividuals...

Occasionally saw this on internet, do anyone think this works? "Hi. This is about an idea of generating electricity by gravitational force. Attached please the basic concept of the idea. The idea consists of two major parts. The first part of the system makes use of electrolysis of...

Homework Statement Mass M is distributed uniformly over a disk of radius a. Find the gravitational force between this disk-shaped mass and a particle with mass m located a distance x above the center of the disk. Homework Equations The problem gives the hint to use the equation found in...

1. Homework Statement [/b] There's a 20kg ball and two 10kg balls 20cm above it. One of the 10kg balls is 5cm to the right of center and the other is 5cm to the left of center. What is the net gravitational force on the 20kg ball 2. Homework Equations [/b] F=GMm/R23. The Attempt at a...

Homework Statement Planet X has a radius double of Planet Y. Planet X also has a mass that is double planet Y. How do the surface gravitational fields of X and Y compare? Homework Equations g=GM/R The Attempt at a Solution So because were looking for the ratio of gx to gy, we can use...

Hello friends ! I got confused in the point that how can a body exert a gravitational force on other body without coming in its physical contact ? Also please explain its mechanism or significance of gravitational force ?

Would I be correct in saying that gravitational force is the force of attraction between any two objects and has the following characteristics: Attractive and the magnitude of the force is inversely proportional to square of distance between the two object It is given by the formula F=GmM/r^2...

I read the proof that for a thin spherical shell with mass M, the potential energy U for a point mass m inside the shell is constant (depending only on the radius R of the shell) and thus the gravitational force on m is 0 at any point inside the shell. Then they talk about a point mass inside...

1- F = mk/r^2 ... k is -ve value ...why ?? please in concise way 2- for escape velocity ... v( inital) = root ( 2gR )... with proof thank u

Say an object is dropped out of a plane at height h above the ground and flying at a constant speed v0... Ignoring air resistance, the only force on the object is the gravitational force, but it will still move in the direction that the plane was moving, right? So if Fg is the only force...

Homework Statement Four spheres of equal 9.5 kg are located at the corners of a square of length 0.6 m per side. Find the magnitude and direction of the gravitational field on one by the other three spheresHomework Equations gravity = GM/r^2 with G = gravitation constant, M = mass, r = radius...

If I take a feather and a rock and drop them at the same time, because of the effect of the gravitational force, we know that the rock will hit the ground first. (The rock experiences a larger gravitational force). My question is if these objects are dropped at the same time and vertically...

apologies if this has been covered elsewhere in the forums, but i was unable to find it. I've seen the usual gravitational force equation [i.e. F=gMm/r^2] with essentially r^3 in the bottom. an example of this can be seen in http://www.mathworks.com/moler/exm/chapters/orbits.pdf on pages 8...

how to solve for mass given gravitational force and radius ? Homework Statement The gravitational force between two identical objects 2.00m apart is 3.50x10^-6N. determine the mass of each object. the answer should be [458kg] Homework Equations i know that Fg= GmM/r^2 so...

I learned the formulas F = G \frac{m_1 m_2}{r^2} and F = m \cdot a and also saw mathematically that objects have the same gravitational acceleration and will fall down at the same rate, also demonstrated in a video by people that were on our moon, even though one object clearly has more force...

Homework Statement Three object A, B and C are placed 5.00 x10^-1 m apart along a straight line. If A and B have equal masses of 10 kg and C has a mass of 15 kg what is the net gravitational force on B due to A and C? Homework Equations Fg= Gm1m2/r^2 Horizontal Fnet= Fa + Fg The...

In the First Three Minutes Weinberg wrote: How would that imbalance actually manifest itself in the real world? Does that mean that if for every 10^36 protons the sun had 10^36 + 1 electrons and if the Earth for every 10^36 electrons had 10^36 + 1 protons, then that would knock the Earth out...

Homework Statement Sphere A with mass 70 kg is located at the origin of an xy coordinate system; sphere B with mass 69 kg is located at coordinates (0.29 m, 0); sphere C with mass 0.40 kg is located at coordinates (0.15 m, 0.11 m). In unit-vector notation, what is the gravitational force on...

Homework Statement Two bags of apples, each containing 20 apples of equal mass, experience a gravitational force of attraction of 200 units when separated by a distance of 25.0cm. If 10apples are removed from one bag and placed into the other bag, and the two bags are separated by the same...

Homework Statement Michael has a mass of 75.0 kg and Elaine has a mass of 55.0 kg. If Michael and Elaine are 2.50 m apart from each other as they sit in their Physics class, determine the gravitational force of attraction between them. Homework Equations I have made a list of equations...