It is night and a wilderness camper is in distress. To signal for help, they take a flare gun into a clearing and fire a flare up from the ground at a speed of 15 m/s.

a) How high does the flare make it into the sky?

b) How long is the flare in the sky?

c) If the surrounding trees are 4 metres high, for how long will the flare be visible above the treetops?

1 answer

the height is

y = 15t - 4.9t^2

So, solve for its vertex (max height), and t when y=0 and y=4 to answer the other questions.