NASA uses the famous “Vomit Comet,” a KC-135 cargo plane, to provide astronauts and scie...

NASA uses the famous “Vomit Comet,” a KC-135 cargo plane, to provide astronauts and scientists a simulated zero-gravity environment. The plane flies a series of parabolic arcs, as shown in the figure. Explain why the passengers feel “weightless” when the plane is near the top of its arc.