I have been asked to determine the length of time the ball will be in the air. I understand the basic concept, but the execution is tripping me up. It has been years since I have done a math course, and this is my first foray into physics, so I am a bit rusty. :) A ball is thrown upwards at a 15 degree angle. Initial velocity is 20m/s. In a previous questions V1(vertical) was determined to be 5.2 m/s. Acceleration is of course -9.81 m/s^2. Equation used: d= v1(t) + 1/2(a)(t)^2 d= 0 a=-9.8 m/s ^2 V1(vert)= 5.2 m/s t= X My efforts: 0=(5.2)t + 1/2 (-9.8)t 0= t (5.2 - 4.9) t=0 So two issues here: 1) I am truly at a loss when re-arranging this equation, I shuffled things around but am not sure it was correct, refresh my memory please! 2) My text states that I should have two answers. I don't understand how I am to get two answers, as they do not suggest I change the equation in anyway. Thank you for helping!