If the airplane has "retractable" landing gear, the wheels and struts fold up inside the wings, or belly, or engine compartment of the plane. Sometimes openings where the wheels go (wheel wells) are covered with doors when the gear is retracted, but sometimes the gear itself has a cover on one side and that's the side that forms the flat surface on the bottom of the airplane when the gear is retracted.
Some small aircraft have "fixed landing gear." Those wheels don't go anywhere. They just hang in the air as the plane flies. These airplanes rarely go over 180 miles per hour, so the gear is not damaged by the wind. With bigger and faster aircraft the gear must be retractable so it is not damaged.
1) An automobile. 2) applecart 3) airplane on the ground
"wheels up" is when an airplane is off the ground. When someone says they are going "wheels up" it means they are flying soon.
With the plane
If you mean like an airplane without wings, there's air resistance, friction between the wheels and the ground, and the axle on which the wheels rotate.
because the ground is solid
Into a container in the plane where it can be removed when the plane is back on the ground.
airplane
Moving an airplane on the ground is called 'taxiing'
They rotate and can be braked, just like auto wheels. Nose wheels can be steered.
road...
3
ten