A qulliq [kudlik] is an oil lamp that functions as the main source of heat and light for an igloo in the Inuit culture. It is made of soapstone shaped as a parabolic bowl that contains seal blubber for the oil. It is lined with arctic wool for the wick. If the length of the bowl is 50cm and the height is 10cm, determine the quadratic function that can be used to model the shape of a qulliq. Express the function in vertex form.