Asked in ScienceAstronomyPhysicsThe Moon
If two bodies of mass are attracted to each other by gravitational force why don't objects stick together?
December 14, 2009 6:35PM
The gravitational force is a very weak one. Actually we only feel earth's gravitational field because the earth's mass is huge. So is the gravitational field of stars and astronomical bodies. But since the objects we usually deal with have really small masses, it's gravitational force is so weak that it gets surpassed by many other forms of force (like friction, for instance). So if you could have a situation where no other forces were involved and you had an equipment precise enough to measure the force you would be able detect the usual object's gravitational force.
If you think about it, objects indeed stick together as a result of gravity. The planets formed (or so we theorize) by the "accretion" of materials floating around the young sun in the very early period of the solar system. At first bits of dust, rock and gas just floated and crashed together, but physical objects of any size have at least some gravity. The larger chunks of rubble attracted one another, and stayed together, giving the now larger object more gravity. And on and on it went until-- Big Ben!
Objects that end up not sticking together are in stable enough orbits not to attract each other to the point of collision. But collisions still do occur, as proven dramatically by the comet collision on Jupiter actually witnessed just a few years ago.
They do. Proportionally to mass. Just try to lift that 1 ton block of concrete by hand!!