Answer:
The velocity of watermelon when it passes Superman is 78 m/s.
Step-by-step explanation:
Height of the building, d = 320 m
Speed of the superman, v = 39 m/s
We need to find the speed of watermelon when it passes Superman. Let t is the time taken by the watermelon. So,

Here u = 0


t = 7.95 seconds
Let v is the speed of the watermelon. It is given by :


v = 77.91 m/s
or
v = 78 m/s
So, the velocity of watermelon when it passes Superman is 78 m/s.