1. The problem statement, all variables and given/known data 1. Neglecting the height of release, a ball is thrown vertically upwards at 20 m/s, find: d) time (s) that the projectile is at height 10.5 m. V1 = 20m/s a = -9.81m/s^2 d = 10.5m 2. Relevant equations d = v1*t + 1/2 a(t^2) 3. The attempt at a solution subsitutiting i can get the formula to: 10.5 = 20t + 1/2(-9.81)t^2 10.5 -20t +4.905t^2 = 0 4.905t^2 - 20t = -10.5 t^2 - 20/4.905 t = -10.5/4.905 However I am rusty on my quadratic equation work and do not know how to solve from here and cannot seem to figure it out? any help would be awesome Thanks in advance.