The Baseball will travel upwards until its velocity is zero andthen fall back down again.The acceleration of the baseball is the constant accelerationdue to gravity acting in a downwards direction.The time taken to fall back down will be the same as the time toclimb, thus the total time is twice the climb time.Use Netwon's equations of motion and ignore air resistance, thetime to the top of the climb is:v = u + at→ t = v - u/av = final velocity = 0 m/s at the top of the climbu = initial velocity = +100 m/sa = acceleration = -g m/s²t_top = 0 - (100 m/s) / (-g m/s²) = 100/g s→ t_total = 2 × t_top = 2 × 100/g s = 200/g s ≈ 200/9.81 s ≈20.4 s