A spring has a length of 30 cm at rest and it elongates by 2cm for a weight of 20N. The spring retains its perfect elasticity as its length does not exceed 40 cm.
a- Calculate the max mass that can be measured with this spring. Please explain your answer.
b- We suspend a weight of 120 N. Is Hooke's law still applicable? Is the length produced by this weight valid? Explain why?