Solve the Problem $$s ( t ) = - 16 t ^ { 2 } + 112 t$$

Multiple Choice

Solve the problem.
-An explosion causes debris to rise vertically with an initial velocity of 112 feet per second. The function $$s ( t ) = - 16 t ^ { 2 } + 112 t$$ describes the height of the debris above the ground, s(t) , in feet, t seconds after the explosion. What is the instantaneous speed of the debris when it hits the ground?

A) 224
B) -224
C) -112
D) 112