For a body on horizontal surface, coefficients of static and kinetic frictions are 0.4 and 0.2 respectively. When the body is in uniform motion on the surface, a horizontal force equal in magnitude to limiting friction is applied on it. The acceleration produced is

When the body is in uniform motion on the surface, force p, acting on the surface is equal to the kinetic frictional force i.e., p = 0.2 x m x g = 0.2 mg. when another force F = f_l = 0.4 x m x g is applied on the body, net unbalanced external force acting on the body F = 0.2 x m x g

Acceleration = F/m = 0.2g