Question

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?

Answer 1

Answer:

One second

Explanation:

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

$h(t)=-16t^2 +0t+ 16$

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

$0=-16t^2 +0t+ 16$

solving equation for t:

$16t^2=16$

$t^2=1$

$t=\sqrt{1}=1$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.