First, lets find an expression for the angle on the whell:
Lets say the 'x' is the angle that our passanger have in a given time. We know that in 40 seconds our passanger travels an angle of:
So, using the rule of three, we can find that in 't' seconds he has an angle of:
now, lets draw again:
So, we can see that the height will be:
But we know the expression for the angle x, so: