Given
K.E = 12\frac{1}{2}21mr_{r}rv2^{2}2
m1_{1}1u1_{1}1 = v(m1_{1}1 + m2_{2}2) [law of conversation of momentum]
v = 0.05×2000.05+95\frac{0.05 \times 200}{0.05 + 95}0.05+950.05×200 = 10ms−1^{-1}−1
K.E = 12\frac{1}{2}21(1)102^{2}2 = 50J