Q4 A bank of soil is being excavated by a backhoe and loaded onto? a dump truck; the truck weighs 13 tonnes and carrying 18 tonnes? payload The soil is being transported to a dump site located (In the top of a 15% inclined soft dirt track with a rolling resistance factor; of 75 kg/tonne. ' What is the total resistance and effective grade when: (a) The truck is moving up hill; and (b) (b) The truck is returning (moving down hill)