Ok, I have some troubles understanding the 3 laws of Newton. 1st law: So if the net force exerted on an object is zero, the object continues in its original state of motion. The net force is the vector sum of all the external forces right? For example a book lying in the table. The net force would be 0 because the book is exerting its weight on the table; therefore the table is pushing back on the book with the same weight. So what if you pushed the book making it move. Would the Net force be equal to 0?? Net forces don't include the force you are acting upon it right? So if the net forces weren't zero. Then would the book just fall through the table? I don't understand this part. Please explain thanks!!