A ball is thrown upwards from the top of a tower `40 m` high with a velocity of `10 m//s.` Find the time when it strikes the ground. Take `g=10 m//s^2`.

Explanation

To solve the problem of a ball thrown upwards from the top of a tower, we can follow these steps:

### Step 1: Define the variables
- Height of the tower (h) = 40 m
- Initial velocity (u) = 10 m/s (upwards)
- Acceleration due to gravity (g) = -10 m/s² (downwards, hence negative)
- Final position when the ball strikes the ground (s) = -40 m (since we take the top of the tower as the reference point where s = 0)

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