For example, if you put a book on the table, then would it be harder and harder to lift the book when you are increasing the weight under the table, on the floor?

 

Since more mass means more gravity between two objects

yes. but the effect is pretty negligble unless you put something increadibly massive under the table, say mars for instance.

Wow - I never thought of it that way. I mean I have but not in that way.

 

Yes - the body underneath the table would have to be bigger than the Earth:D

yes. but the effect is pretty negligble unless you put something increadibly massive under the table, say mars for instance[/b'].

lol

the body underneath the table would have to be bigger than the Earth

 

not really. anything would have an effect but it wouldn't be very noticable until its a good fraction of the mass of the moon.