Question

N one amusement park ride, riders enter a large vertical barrel and stand against the wall on its horizontal floor. The barrel is spun up and the floor drops away. Riders feel as if they are pinned to the wall by a force something like the gravitational force. This is a fictitious force sensed and used by the riders to explain events in the rotating frame of reference of the barrel. Explain in an inertial frame of reference (Earth is nearly one) what pins the riders to the wall, and identify all of the real forces acting on them.

a) Centrifugal force pins riders; gravitational and normal forces act on them.
b) Gravitational force pins riders; only normal force acts on them.
c) Normal force pins riders; gravitational and centrifugal forces act on them.
d) Centripetal force pins riders; gravitational and normal forces act on them.

Answer 1

The riders in the barrel ride experience a normal force from the wall, which provides the centripetal force for circular motion, while gravity also acts on them. There is no actual centrifugal force in the inertial frame of reference.

Step-by-step explanation:

Understanding Forces in a Rotating Frame

When riders in an amusement park barrel ride feel as if they are being pinned to the wall, the sensation is due to the wall exerting a normal force on them. This force acts perpendicular to the wall's surface and provides the necessary centripetal force to keep the riders in circular motion.

In contrast to what riders might perceive, there is no centrifugal force acting on them in the inertial frame of reference; this is a fictitious force that only appears in the rotating frame. The only real forces acting on the riders are the gravitational force pulling them towards the Earth's center and the normal force from the wall, which provides the centripetal force necessary for their circular motion.