This is a downward-curving path with the center of the curve below the slide. The centripetal acceleration is in the downward direction.
The normal force has to be less than the radial component of the force to pull the person down. The normal force gets smaller.
There needs to be a net force pointing towards the center of the circle in order for a rider to move in a circular path. The centripetal force is composed of the normal force pushing away and the part of the force pulling towards the center.
You don't need a large centripetal force to move a rider if they are slow. The component of the force is enough to get it. The force from the slide might be small.
The force of gravity alone wouldn't be enough to produce circular motion if the rider got too fast. The normal force is needed to pull toward the center of the circle. The slides don't do that. The sliding human wouldn't actually move in a circle, but instead along a parabolic path as they leave the slide and become airborne, until they crash back into the slide. It happened to the slide riders.
A person is sliding down a slide. The rider is at the top of a curve. At some point the person flies off the track and into the air.
The speed at which the person begins their ride is crucial. The value for the speed that will cause a person to come off the slide depends on the start and end of the slide.
If you want your riders to stay on the slide, you need to increase the coefficients of friction between them. The Michigan Department of Natural Resources, which runs the park, posted a video on their Facebook page explaining the changes they have made. A park employee shows the riders how to lean forward.
What is the reason for water? Adding a small amount of water could cause it to become more sticky. Adding enough to create a full-on waterslide would take a lot of water, so it's not a good idea.
If the rider's weight is on the cloth sack on their legs, it will be safe. Because all the riders have to wear these sacks, it makes for a more consistent surface, which makes for a better experience. If they leaned backwards, the material that makes up the person's shirt would be in danger.
If the park operators want to get even more creative, another option would be to have riders wear something other than the sacks and slide. It is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556 is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556
I'm happy sliding.