Mass of the block = 1.4 kg
Weight of the block = mg = 1.4 × 9.8 = 13.72 N
Normal force from the surface (N) = 13.72 N
Acceleration = 1.25 m/s^2
Let the coefficient of kinetic friction be μ
Friction force = μN
F(net) = ma
μmg = ma
μg = a
μ = [tex]\frac{a}{g}[/tex]
μ = [tex]\frac{1.25}{9.8}[/tex]
μ = 0.1275
Hence, the coefficient of kinetic friction is: μ = 0.1275