A model rocket is launched with an initial upward velocity o

A model rocket is launched with an initial upward velocity of

47/ms

. The rocket\'s height

h

(in meters) after

t

seconds is given by the following.

=h47t5t2

Find all values of

t

for which the rocket\'s height is

27

meters.

Solution

Assuming height H at initial velocity as u =47/ms and final is v for upward movement

By newton\'s second law

H= ut + 1/2 gt²

27 = 47t - 5t² ( g = -10/ms² for retardation)

5t² - 47t + 27 =0

t =(47-1669)/10= 0.615

t =(47+1669)/10= 8.785