text: what is the specific gravity of grvel, sand?   gravity affects every single object on earth in the same way, by a pull of approximately 9.8 meters/sec squared, of course you have to take into account wind resistance, therefore an object such as a truck going off a building will drop slower than that of a baseball because the wind resistance will affect the truck more. so sand, gravel, the specific gravity is 9.8 meters/sec ( in a vaccuum, meaning where there is absolutely no air resistance but since places that this aren't normal you have to assume wind resistance.)