1. The problem statement, all variables and given/known data a body of mass 10 kg lies on a rough horizontal surface with an acceleration of 5 m/s and when the horizontal force us doubled , it gets an acceleration of 18 m/s^2. Then the coefficient of friction between the body and the horizontal surface is: A) 0.2 B) 0.8 C) 0.4 D) 0.6 2. Relevant equations fnet = f - umg = ma1 1st case Fnet = F - umg = ma2 2nd case 3. The attempt at a solution I tried to solve it but u comes out to be zero.