Objects are pushed or pulled by forces acting on them. Contact force is defined as the force exerted when two physical objects come in direct contact with each other. Other forces, such as gravitation and electromagnetic forces, can exert themselves even across the empty vacuum of space.
It's quite common for most professionals to use Photoshop on the daily. I know a few GFX artists and the majority/all of them use Photoshop for making images. I hope I helped! :)
