Question

A rock is dropped from a 400 ft building. The equation for

height as a function of time is h(t) = -16t2 + initial height,
where t is time in seconds and h(t) is height in ft.
How long will it take for the rock to hit the ground?
What value should we use for "h(t)"?
A
0, because when the height of the rock is 0, it
will hit the ground
B
400, because that is the height of the building
that the rock falls off of

Answer 1

A

h(t) is height of the rock as time passes. We want to solve for t when h = 0 (When rock hits ground) so we solve for h(0), or 0.