તેથી, \({\text{W}}\,\, = \,\,\frac{{\text{1}}}{{\text{2}}}\,\,kx_2^2\,\, - \,\,\frac{1}{2}\,kx_1^2\,\, = \,\,\frac{1}{2}\,k\left( {x_2^2\,\, - \,\,x_1^2} \right)\)
\( = \,\,\frac{1}{2}\,\, \times \,\,800\,\,\left[ {{{\left( {\frac{{15}}{{100}}} \right)}^2}\,\, - \,\,{{\left( {\frac{{15}}{{100}}} \right)}^2}} \right]\,\, = \,\,8J\)