Question
A Ferris wheel is loaded with people in the chairs at the following positions: 4 o'clock, 1 o'clock, 9 o'clock, and 6 o'clock. As the wheel begins to turn, what forces are acting on the system? How will each force affect the angular velocity and angular momentum?
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Solution video
OpenStax College Physics for AP® Courses, Chapter 10, Problem 2 (Test Prep for AP® Courses)
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Video Transcript
This is College Physics Answers with Shaun Dychko. A Ferris wheel is loaded with people positioned at 1 o'clock, 4 o'clock, 6 o'clock and 9 o'clock and as the wheel begins to turn, what forces are acting on the system and how will each force affect the angular velocity and angular momentum? So we have a force due to the motor, which will have to be perpendicular to some point of this Ferris wheel maybe it's going to be applied here say and perpendicular to the radius. So it's going to tend to accelerate the Ferris wheel and increase its angular velocity and angular momentum. The force of gravity on person positioned at 1 o'clock, this is exerting a clockwise torque and so it will tend to decrease the angular velocity and momentum and likewise for the person positioned at location 4. The force of gravity on the person at position 6 exerts no torque and so it will have no effect on the angular velocity or angular momentum initially and this force of gravity of the person at position 9 will be tending to increase both angular velocity and momentum because it's going in the same direction in terms of the torque— the torque is counterclockwise, just like the torque exerted by the motor.