Block stops when net force on block is zero. ⇒ Component of weight along incline = Spring force ⇒mg‌sin‌θ=kx Substituting m=10‌kg,θ=45∘ k=100√2Nm−1, we get 10×10×sin‌45∘=100√2×x ⇒x=0.5m As, unstretched length of spring is0.8m, total length of spring (or distance of block from top) in equilibrium, l=0.5+0.8=1.3m