Nothing would happen. The carriage would simply remain stationary on the rail - without any propulsive force to move it forwards or backwards, and without any gravitational force to cause it to fall.
If there was no force of friction, the monorail would not be able to grip the tracks and would likely slide off or lose traction, leading to a loss of control. Friction is essential to enable the wheels of the monorail to maintain contact with the track and provide the necessary traction for movement.
Friction between the wheels and the tracks, as well as air resistance, are the primary forces that slow down a monorail. Additionally, braking systems in the monorail cars are used to further control and slow down the speed of the train.
Carowinds Monorail ended in 1994.
Carowinds Monorail was created in 1973.
Sentosa Monorail was created in 1982.
Sentosa Monorail ended in 2005.
Tokyo Monorail was created in 1964.
Kitakyūshū Monorail was created in 1985.
Okinawa Monorail was created in 2003.
Metro Monorail was created in 1988.
KL Monorail was created in 2003.
Moscow Monorail was created in 2004.