8) (15 points) A child drags her toy box (m = 4 kg) up a hill by applying a force F = 25î + 3ſ(N). The surface of the hill is rough where the coefficient of kinetic friction is uk = 0.34. At the beginning of the hill, her speed is 1.5 m/s. Taking upward direction along the surface of the incline as the positive x-direction, answer the following questions. a) What is the work done by the child's force for the entire track? b) What is the work done by friction? c) What is her speed at the top of the track? h =3 m 0 = 20° Answers: a) Wc = J, b) W = -100.89 J, c) Vj = 1.62 m/s 9) (15 points) An object of mass 4 kg is pulled up on an inclined plane by a force ? = 54î - 16ị N. If the coefficient of kinetic friction of the inclined surface is uk = 0.25, find a) the work done by force F, b) the work done by gravitational force, and c) the work done by frictional force. d=8.2 m 37°