To put it simply, scalar is essentially just a number of the force, such as 10 newtons whereas a vector is a force with a direction such as 10 newtons south
In physics,there is nothing like strong force. Every force has a scientific name. For examples,the force between two surfaces is friction,the force existing in fluid is viscosity,the force exing in...
Without going into advanced physics, just consider it an action at a distance. The objects don't need to be touching directly for the force to be transmitted.