premise: fuel is a source of mechanical energy for cars to move sent2: if an object is not moving it does not have any motion to counter sent3: a car is moving on a level road sent4: if an object has 0 mechanical energy, then the object will stop moving sent5: the car runs out of fuel sent6: if one surface is moving on another surface then those surfaces are touching sent7: friction acts to counter the motion of two objects when their surfaces are touching sent8: if something is decreased and there is no source of that something to provide more of that something, then that something will decrease to 0 sent9: countering the motion of a moving object means decreasing the mechanical energy of the moving object.
hypothesis: the car will stop when the mechanical energy in it is decreased by friction to 0