In the expression \(-16t^2 + 40\), which is used to evaluate the height of the egg in relation to time \(t\), the number \(40\) represents the initial height from which the egg is dropped.
Since the experiment is conducted from the top of a 40 ft tall building, this indicates that at \(t = 0\) (the moment the egg is dropped), the height of the egg is 40 feet. As time progresses, the height decreases due to the effect of gravity, which is represented by the \(-16t^2\) term in the equation (where -16 is derived from the acceleration due to gravity in feet per second squared).