One of the great advantages of working in space is that objects, including the astronauts themselves, have no apparent weight. Regardless of the weight of an object on Earth, a single crew member can move and position that object in orbit with ease provided the crew member has a stable platform from which to work. The physics of working in space is the same as that of working on Earth. All people and things contain matter and consequently have mass. Because of that mass, they resist any change in motion.
Physicists refer to that resistance as inertia.
The greater the mass, the greater the inertia. Like on Earth, to change the motion of objects in space requires an application of force. How much the object moves is explained in part by Sir Isaac Newton's Third Law of Motion. The law states that a force causing an object to move one way is met with an equal and opposite force in the other direction. The consequence of this law in space is important.