A ball is thrown from a height of 123 feet with an initial downward velocity of 11 ft/s. The ball's height h (in feet) after t seconds is given by the following.

h(t) = 123 - 11t - 16t^2

This is because the initial height of 123 feet is subtracted from the equation, and the downward acceleration due to gravity is -16 ft/s^2.