### Home > CALC > Chapter Ch7 > Lesson 7.3.5 > Problem 7-159

7-159.

A Ferris wheel, 50 feet in diameter, revolves at a rate of 2 radians per minute. How fast is a passenger moving vertically when the passenger is 15 feet higher than the center of the Ferris wheel and is rising? Homework Help ✎

Sketch a diagram. Assume the wheel is rotating counterclockwise and let the passenger be at acute angle *θ* and height *H* above a horizontal radius. Do you see the right triangle? Write a geometric equation relating H and θ? Then implicitly differentiate the equation with respect to time.

Determine the value of cos(*θ*) when *h* = 15 ft.

Once you compute this value, use the differential equation to solve the problem.