Answer:
The value
![t = 1.995 \ s](https://img.qammunity.org/2021/formulas/physics/high-school/p2uf2b9pscbxdwpioxj3qnfps0uzjq9yjr.png)
Step-by-step explanation:
From the question we are told that
The acceleration due to gravity is a = 2g
The maximum height is h= 39 m
Generally from the kinematic equation
![s = ut + (1)/(2) at^2](https://img.qammunity.org/2021/formulas/physics/high-school/sw3g8o6k7tgow1s0d413h564sm6vjo7c0n.png)
Here u is the velocity of the ball at maximum height before it start falling and the value is 0 m/s
So
![39 = 0* t + (1)/(2) (2g)t^2](https://img.qammunity.org/2021/formulas/physics/high-school/tf9lbvqk2yzlh4m06ql7qec7fkai3fotal.png)
![39 = (9.8)t^2](https://img.qammunity.org/2021/formulas/physics/high-school/kkaaue4kr3sst1owe64tnyalu5tcqg4zxi.png)
![t = √(3.9795918)](https://img.qammunity.org/2021/formulas/physics/high-school/9c0ncaknkjm11xm7dr2x2pkb5e3o5qg7xf.png)
![t = 1.995 \ s](https://img.qammunity.org/2021/formulas/physics/high-school/p2uf2b9pscbxdwpioxj3qnfps0uzjq9yjr.png)