In one amusement park ride, riders enter a large verticalbarrel and stand against the wall on its horizontal floor. The barrel is spun up and the floor drops away. Ridersfeel as if they are pinned to the wall by a force somethinglike the gravitational force. This is a fictitious forcesensed and used by the riders to explain events in therotating frame of reference of the barrel. Explain in aninertial frame of reference (Earth is nearly one) whatpins the riders to the wall, and identify all of the realforces acting on them.