A competitive diver executes a double somersault with a twist from a platform. Her height above the water t seconds after leaving the board is given in feet by h = − 16 t 2 + 0 t + 16 How long does she have to complete her somersault before entering the water?

One second

Explanation:

Her height above water as function of time after leaving the board is:

When she enters the water the height above the board is zero so h(t)=0, using that on (1):

solving equation for t:

s

Mathematically there're in fact two possible values for t, -1 and 1 but because we're talking of time negative sign has no physical sense then we only use 1.