Question

At which point will the riders experience centripetal acceleration?

Answer 1

As we know that centripetal acceleration is given as

$a = \frac{v^2}{R}$

so here we all know that radius of curvature of straight surface or flat surface is infinite or very large

So here acceleration will be zero when it move on flat surface

So here at points "w" , "x" , "z" the surface will be flat surface

and hence the observer will not experience centripetal acceleration

while at point Y the surface is curved and hence the observer will experience centripetal acceleration