what is the source of  forces in the nature?
605414
According to one theory there are particles, which are exchanged and travel between the objects, giving impression that objects attract or repel each other. Nothing is proved yet and it is just a theory, as far as my knowledge is concerned.
187737
Actually there are four fundamental forces.  There are two kinds of nuclear force, strong and weak.  Also don't forget magnetism, you should say the electromagnetic force instead of electrostatic only.  Anyway, nobody knows the answer to this question yet.  It is still one of the outstanding questions in physics.  So have fun thinking about it, and see if you can come up with the answer.
987930
No energy source? What source of energy is needed? And the simple presence of mass causes gravitons. And these gravitons interact with one another. And proof, you need proof that gravity works? Dude go jump off of a building and see what happens!
66345
Yeah, gravity.  That's what slings everything around.  The enormous mass of the sun gives it an incredible gravitational pull.
654890
The greater the pressure difference, the stronger the pressure gradient, hence the stronger the pressure gradient force.\n\nPressure gradient force is responsible for triggering the initial movement of air, which in turn leads to the development of wind. It is directed from higher to lower pressure at right angles to the equal pressure surfaces, isobars. The closely spaced isobars in a weather chart indicate steep pressure gradients, strong forces, and high winds, while widely spaced isobars indicate gentle pressure gradients, weak forces, and light winds.\n\nBernoulli's Principle............
122737
Gravity is an example of a natural law. Something about two objects being attracted to each other.  Water molecules will form drops of rain because the molecules are attracted to each other.  Gravity is the result of a really large mass attracting other objects - earth holding moon in orbit, sun holding earth in orbit.  gravity is proportional to the size of the mass in question, sun's gravity is stonger than earth's and moon's gravity is weaker than both.
794968
.  Gravity and magnetism are two very different kinds of forces.  Gravity is always attractive and is proportional to the masses of two objects and how close together they are.  Magnetism can be attractive (pulling objects together) or repulsive (pushing them apart).  Magnetism is due to electric fields, either in the atoms of certain materials or electric fields resulting from electric currents in a sizable quantity of material.\n.  The earth might be a large magnet, with a net magnetic orientation in its solid iron inner core making the core a magnet, but its magnetic field is due mostly due to electric currents in the molten iron outer core which are generated by interactions with other magnetic fields.  We know that the earth is not like a permanent magnet because its magnetic field reverses periodically, about every 100,000 to 200,000 years.\n.   There are four basic forces in physics: gravity, the electromagnetic force, the weak nuclear force and the strong nuclear force.  Gravity seems to be quite different from the other forces.  Quantum mechanics can explain the other three forces and demonstrate how, at very high particle energies, they could be a single force.  Gravity,so far, can not be united in theory with the other forces.
332766
Force is a vector quantity as it has both magnitude (size) and direction.
53644
The same 4 fundamental forces in the universe: Strong, weak, electromagnetic and gravity. Of course, it should be noted that we have made substantial progress into showing that the weak and electromagnetic forces are two aspects of the same force, and that even the strong force can be associated very closely with the electroweak force. There are many attempts to connect all 4 forces into one universal force law, but this effort is not yet complete and the results are not yet universally accepted. \n\nThere are some indications that we do not really understand gravity very well, because we do not understand its quantum aspects too well, and there is even evidence emergy for some sort of repulsive gravitational phenomenon from astronomical observations. \n\nThe discovery of any other forces would be quite surprising, and very big news.
338445
The net external force acting on a particle is equal to the product of the mass and its acceleration.\n\nF = ma\nwhere, F = the net external force\n       m = the mass of the particle\n       a = the acceleration of the particle
1053094
What you're describing is called the 'grand unified theory,' or GUT. There are four known fundamental forces in nature that literally control everything--gravity, electromagnetism, the weak nuclear force, and the strong nuclear force. Science has been successful in uniting all of these except gravity.
827409
We know of four types of fources, gravitational, electromagnetic, strong and weak forces. gravitational force will be there whereever massive bodies are present. If electrically charged bodies are present then electromagnetic force will also be there. Strong nuclear and weak forces are also likely to be there between subnuclear particles. So I guess all four forces will be present at the planets you mention.
1058239
Yeah, force is just energy applied on a particle. Force per time is power.
466570
Mass.\n\nF=ma\n\nF is the force\nm is the mass\na is acceleration
675323
Every atom has gravitational forces, also known as the "VanderWaal force". This force is linearly related to the mass of the particle. As the mass grows (a cluster of particles, an object, a planet) the gravitational force gets larger, being the sum of all individual gravitational forces. The gravitational force only influences objects that have a mass of there own. So a ball is attracted by the Earth and the ball attracts the Earth.
30388
Gravity, the strong nuclear force, the weak nuclear force, and electromagnetic force.
1140497
Gravity holds things with mass together.\n\nElectromagnetism holds things with unlike electric charges together.\n\nThe strong nuclear force holds things with colour charge together over short range.\n\n\nHope this helps!\nThe Chicken