When you are travelling downhill on a roller coaster, you experience a light feeling in your stomach. why?

when you are travelling downhill on a roller coaster, you experience a light felling in your stomach because, at the time of travelling downhill for a very little duration the roller coaster is falling freely on the earth, and for that time period there is no gravity works on you, and you feel the condition of weightlessness that's why you feel light in your stomach.