Why must curved roller coaster tracks on a be banked?

To counteract inertia and prevent the train from derailing.

When a roller coaster train moves along a curved track, it experiences inertia, which is the tendency of an object to resist any change in its motion. This inertia causes the train to want to continue moving in a straight line, which would result in it derailing. To prevent this, the tracks are banked, or tilted inward, toward the center of the curve. This banking creates a force called centripetal force, which pulls the train inward and keeps it on the track.

The amount of banking required depends on the speed of the train and the radius of the curve. The faster the train is moving, the more banking is required. The tighter the curve, the more banking is required.

Banking is an essential safety feature on roller coasters. It prevents the trains from derailing and keeps the riders safe.