A spiral spring has a length of 14cm when a load of 4N is hung on it.A force of 6N extends the spring by 4cm.calculate,the length of the spring.if a force of 3N is hung on it;assuming hooke's law is obeyed

Answer 1

F = k (L - Li)
6 = k (4)
k = 6/4 = 3/2 Newtons/ cm extension

4 = (3/2) ( 14 - Li)
4 = 21 - 1.5 Li
1.5 Li = 117
Li = 11.33 cm initial length of spring with no force
so
3 = 1.5( L - 11.33)
3 = 1.5 L - 17
1.5 L = 20
L = 13 1/3 cm