It is gravitational force that is responsible for the movement of an object in downward direction and the force is applied between any two objects. The reason behind their being attracted towards downward direction is that the earth has the major share of gravity on earth and which is why it attracts every thing towards itself. It is not only responsible for pulling things towards itself but also we are able to stand on the earth because of this very gravitational force.
You might have seen the researchers that are going into space and when they send their pictures to the earth we find that they are not able to stand at one place. The reason is that there is no gravitational force applicable in the space and it makes the astronomers float in the spacecraft.
You might have seen the researchers that are going into space and when they send their pictures to the earth we find that they are not able to stand at one place. The reason is that there is no gravitational force applicable in the space and it makes the astronomers float in the spacecraft.