the instruments attached to a weather balloon have a mass of 5.0 kg. the balloon is released and exerts an upward force of 98 N on the instruments.

(a) what is the acceleration of the balloon and instruments? (answer is 9.8 m/s^2.. just don't know how to get there..)
(b)after the balloon has accelerated for 10.0 s, the intruments are released. What is the velocity of the instruments at the moment of their release?
(c) what net force acts on the instruments after their release?
(d) when does the direction of the instruments velocity first become downward?