A balloon is released 15 feet away from an observer. The balloon is rising vertically at. a rate of 2 ft/sec and at the same time the wind is carrying it horizontally away from the observer at a rate of 3 ft/sec. At what speed is the angle of inclination of the observer's line of sight changing 5 seconds after the balloon is released?

S = (v-u) / 2 * t, where v is the final velocity, u is the initial velocity, s is the displacement and t is the time.

40 = (v-2.8) / 2 * 8.5

4.71 = v-2.8/2

9.41 = v - 2.8

v = 12.2 m/s

v^2 = u ^2 + 2as where v is the final velocity, u is the initial velocity, a is the acceleration and s is the displacement.

12.2^2 = 2.8^2 + 2a (40)

80a = 12.2^2 - 2.8^2

80a = 148.84 - 7.84

80a = 141

a = 1.7625m/s^2