Hello!

The height of the watermelon above the ground is

`H(t)=H_0+V_0*t-(g*t^2)/2,`

where `H_0=1.2m` is the initial height, `V_0=9.5m/s` is the initial upward velocity and `g=9.8m/s^2` is the gravity acceleration.

Its velocity is

`V(t)=V_0-g*t`

and its acceleration is `g` (a constant).

The watermelon reaches the peak of its flight when H(t) has its maximum. It is reached at `t_1=V_0/g` (the property of a quadratic function).

(**a**) its velocity at that time is **zero**, which isn't a surprise. Actually, zero velocity is the equivalent condition for "the watermelon reaches the peak of its flight".

(**b**) its acceleration is **g** all the way, and also at a peak.

(**c**) time elapsed is `t_1=(V_0)/(g) = (9.5)/(9.8) approx` **0.97 (s)**.

(**d**) the height above the ground is `H(t_1)=1.2+9.5*0.97-(9.8/2)*(0.97)^2 approx` **5.8 (m)**.

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