If its a 4x4 it's in neutral probably
When a horse pulls a wagon, the force that causes the horse to move forward is the force of traction generated by the hooves gripping the ground. This force propels the horse and wagon forward by overcoming the friction between the hooves and the ground.
It being in neutral or park.
Your gear linkage is offset!! Or you are on a steep down hill
That would be your transmission. It may be slipping, or you may be lossing a gear. Have it checked.
noise
When they move over dry land they begin to lose power.
there are many causes for this. You should consult a ASE trained technician.
Whatever gear will make the vehicle move away from the airplane if it starts to move under its own power with no one at the controls.
the engine does run chances are that the speedometer cable is broken or the gear in the transmission is striped
If you move from a big chainwheel to a smaller chainwheel by the pedals, pushing the pedals will get easier. If you move from a big sprocket to a smaller sprocket by the rear wheel, pushing the pedals will get heavier.
either your shift sensor is bad or the tranny is shot
truck start shift is hard to move in gear