A ball is projected upwards from a platform 8m above the ground,with an initial velocity of 3m/s.How long does it take for the ball to reach the ground.

Answer 1

h = Hi + Vi t - 4.9 t^2
0 = 8 + 3 t - 4.9 t^2

t = [ -3 +/- sqrt (9+157) ]/-6

t = [ - 3 + / - 12.9 ] / -6

= -.5 +/- 2.15

= 1.65 seconds