**·**2018-06-11 19:01:16

Spring constant for original spring is -

K=W/9

Since, K is inversely proportional to length,

Therefore spring constant of spring of length 40cm is

=60/40 K =3/2K

And that for spring of length 20 cm is

=60/20K =3K

Combination of two springs is

3/2K + 3K = W

9/2 K = W

We know that K=W/9

So W=9/2K*x

9K = 9/2K*x

X=2cm