What additional load will be required to cause the extension of 2.0cm when an elastic wire extend by 1.0cm when a load of 20g range from it ​

The additional load is 20g

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue