An elastic spring under tension of $$3 \mathrm{~N}$$ has a length $$a$$. Its length is $$b$$ under tension $$2 \mathrm{~N}$$. For its length $$(3 a-2 b)$$, the value of tension will be _______ N.

Two blocks of mass $$2 \mathrm{~kg}$$ and $$4 \mathrm{~kg}$$ are connected by a metal wire going over a smooth pulley as shown in figure. The radius of wire is $$4.0 \times 10^{-5} \mathrm{~m}$$ and Young's modulus of the metal is $$2.0 \times 10^{11} \mathrm{~N} / \mathrm{m}^2$$. The longitudinal strain developed in the wire is $$\frac{1}{\alpha \pi}$$. The value of $$\alpha$$ is _________. [Use $$g=10 \mathrm{~m} / \mathrm{s}^2$$]