The acceleration of gravity on Earth is 9.8 meters per second every second. So
in 1.1 second of falling, an object gains (9.8 x 1.1) = 10.78 meters per second of
downward speed.
The balloon was already falling at 5 m/sec when the time began, and it gained
another 10.78 m/sec on the way. So at the end of 1.1 second, its downward
speed was (5.0 + 10.78) = 15.78 m/sec.
Its velocity was 15.78 m/sec downward.
