A car moving with a high speed at the bottom of a hill (initial state) runs out of gas and gradually coasts to a stop as it moves towards the top of the hill (final state). Ignore all frictional forces. What is the reason for the car to gradually coast to a stop as it moves towards the top of the hill?
1) The car loses its kinetic energy as it moves up the hill
2) The car gains potential energy as it moves up the hill
3) The car experiences an increase in frictional forces as it moves up the hill
4) The car's engine stops working as it moves up the hill