A spiral spring has a lenght of 14cm when a load of 4N is hung on it.A force of 6N extends the spring by 4cm.calculate the unstretched lenght of the spring.

Answer 1

xi is initial length
x is total length with stretch
x-xi is stretch
F = k(x-xi)
4 = k (14 -xi)
6 = k(4)

k = 6/4 = 3/2
4 = (3/2)(14-xi)
8 = 42 -3xi
3 xi = 34
xi = 11 1/3

Answer 2

A spiral spring extends by5 cm under a load of 60N when the load is replaced by a still block then new extension is 7cm . Caculate the weight of the still block