Indrajit Yadav

In the air, there's nothing holding the body of the helicopter still - so the rotor blades spin one direction, butthe torque applied to spin the rotors tries to spin the bodyof the helicopter in the opposite direction. The little rotor on the tail helps keep the body of the helicopter pointed in the same direction.

Balance on a bicycle is a matter of constantly correcting against falls, and it's easier when thespeed is higher because the inertia of moving forward overcomes the need for corrective actions.