You promised your younger brother that you would give him a ride on his sled. (Take the positive î direction to be to the right and the positive ĵ direction to be upward.) (a) You first pull him with a force F1 = 54.0î + 28.0ĵ N. If the mass of the sled and boy is 59.0 kg and the coefficient of kinetic friction is 0.056, what is the acceleration of the sled? Express your answer in vector form. ax = Did you apply Newton's second law for motion in the vertical and horizontal directions separately? How is friction force related to the normal force? m/s2 (b) After a while, you decide to push him from behind with a force F2 = 54.0î − 28.0ĵ N. Determine the acceleration of the sled now to see if it will be different from your answer in part (a). Express your answer in vector form. ax =