Question

A flare is launched from a life raft with an initial velocity of 192 ft/sec. How many seconds will it take for the flare to return to the sea if h = 1 9 2 t − 1 6 t 2 represents the height of the flare in feet above the sea t sec after it is launched?

Answer 1

We use the formula,

$h= ut- 16 t^2$

Here, h is the  variable  represents the height of the flare  in feet when it returns to the sea so, h = 0 and u is the initial velocity of the flare, in feet per second and its value of 192 ft/sec.

Substituting these values in above equation, we get

$0 = 192 t - 16 t^2 \\\\ 16 t( 12 - t ) =0 \\\\ t = 12 s$.

Here, t= 0 neglect because it is  the time when the flare is launched.

Thus, flare return to the sea in 12 s.