6. A 15000 kg bus is travelling at a constant speed of 6.2 m salong a section of road that is inclined at an angle of 6.0 to the horizontal. 6.0 (a) (i) The bus is represented by the black dot shown below. Draw a labelled sketch to represent the forces acting on the bus. (b) (ii) Write a formula to determine the force of friction acting on the bus. Using your answers in part a (i) and (ii), determine the coefficient of friction between the bus' tires and the ground.