Using Newton's second law: F - f = ma 10 - f = 2(3) f = 4 N

Using the kinematic equation: v = u + at v = 10 + 2(5) = 20 m/s

v'₂ = 2v₁ / (m₁ + m₂) v'₂ = 2(5) / (2 + 3) = 2 m/s