Question

a small rock falling from the top of a 120 ft tall building with an intial downward velocity of -30 ft/sec is modeled by the equation h(t)=-16t-30t+124 where t is time in seconds. For which interval of time does the rock remain in the air

Answer 1

Answer:

The rock remains in the air for t = 3.832 s

Step-by-step explanation:

To easily solve this equation, we can graph the equation with a calculator and see the interval for which the rock remains in the air.

(There is a minor problem with the equation, the last term should be 120 to model the 120 ft building)

h(t)= -16t^2 -30t + 120

Please see attached picture for the graph.

The time it takes for the ball to hit ground can be found by making

h(t) = -16t^2 -30t + 120 = 0

In the graph this point is equal to

t = 3.832 s

h(t) = 0