[John2022]

But nowhere (at least in the first couple of levels) does it refer to the slope of the mountain - it says the task is to find "the path of the sled".

But even ignoring that, nowhere does it define the relationship between t and x. What I assume they mean but don't say is that x=t. That's arbitrary.

Also I assume you mean the path of the sled is (t, f(t)) where f is the function defining the slope. If the path of the sled had a value of (x,y) it would be stationary :)

[dylan604]

Seeing how the shape of the mountain IS the path of the sled, how does changing the shape of the mountain NOT change the path for you?

[Nevermark]

The path is flat by default, and mostly flat by initial expression. So it might not strike someone that the shape of the path is a mountain shape.

Perhaps "the shape of a path down a mountain" would make everyone happy.