6. If an airplane does a vertical loop in the air, with a circular arc of radius 273 meters, then what speed does the plane have to go for the pilot to experience (a) versus (b) as stated below. [ASSUME: The pilot experiences forces (e.g. normal force) within their own "pilot's cabin" reference frame. Also, they are seated upright at the bottom of the loop and upside-down at the top of the loop (see diagram below). ] (a) They experience "2 g's" at the bottom of the loop. (b) They experience "weightlessness" at the top of the loop. (c) Explain your answers to (a) and (b) above, with word-explanations and accompanying labelled diagrams