1. The problem statement, all variables and given/known data A body of mass 50 g is dropped from a height of 20 m. A boy on the ground hits the ball vertically upwards with a bat with an average force of 200 N, so that it attains a vertical height of 45 m. The time for which the ball remains in contact with the bat is (g = 10 m/s^2) 2. Relevant equations F= ma v^2 = u^2 + 2gh h = -ut +1/2 at^2 3. The attempt at a solution v = √2gh = √2*10*20 = 20 m/s This will become 'u' for the second part. h = 45 m a = F/m = 200 / 50 / 1000 = 4000 m/s^2 I substituted u, h & a in h = -ut + 1/2 at^2 I didn't get the answer which is 1/80th of a second. I have tried using it by impulse method also. Like, impulse = change in linear momentum = f * dt mv - mu = f * dt u = 20 m/s I calculated v by v = √u^2+2gh = 10 √13 I still didn't get the answer. I cannot understand where I am going wrong.