A ball is thrown vertically upwards. Which of the following plots represents the speed-time graph of the ball during its flight if the air resistance is not ignored?

If the air resistance remains constant during the whole journey of the ball, then velocity of the ball at any time t is given by v = (u - at) where a = (g+ R/m) in upward journey and a = (g - R/m) in downward journey. speed |v| = (u - at) for t ≤ u/a and |v| = (at - u) for t ≥ u/a. Therefore option (3) is right.