Cooper Section $8\mathrm{.}12$ #$6$

$An$ object $is$ dropped out $ofan$ airplane. The height $of$ the object $t$ seconds after being dropped $is$

$h(t)=2000-5t^2$ meters.

$a.$ What was the height $of$ the plane when the object was dropped?

meters

$b.$ What $is$ the velocity $of$ the object $att=3$ seconds?

$\frac{m}{s}$

$c.$ What $is$ the acceleration $of$ the object $att=3$ seconds?

$\frac{m}{s^2}$

$d.$ After how many seconds did the object hit the ground?

seconds

$e.$ How fast was $it$ going when $it$ hit the ground? $(Your$ answer should $be$ negative.$)$

$\frac{m}{s}$