Physics problem super hard?

Question

The instruments attached to a weather balloon have a mass of 5.5kg. The balloon is released and exerts an upward force of 97.7 N on the instruments. Acceleration of gravity is 9.8 m/s^2
What is the acceleration of the balloon and the instruments? Answer in units of m/s^2.
Also after the balloon has accelerated for 10.5 s, the instruments are released. What is the velocity of the instruments at the moment of their release.? Answer in m/s.
Assume: The upward direction is positive. What net force acts on the instruments after their release? Answer in N.
How long after their release does the direction of their velocity first become downward(negative)? Answer in units of s.

Pleaseeeee explain, i am desperate i spent 10 hours on 5 problems and i haven't solved not one! please help

Yes it would help because i have no idea how to do it ive spent so much time on this.. i cant figure it out. I am so upset.

Answer 1

Acceleration of Balloon and Instruments
Net Force (F)= Force up (Fu) + Force of Gravity (Fg)
F=Fu+Fg
Fu=97.7 N
Fg=mg=5.5kg* -9.8m/s^2
Note: I made "g" negative because it is in the opposite direction of motion -- it slows things down.
F=97.7 N - 5.5*9.8 N= 43.8 N
Now
F=ma
a=F/m
a=43.8/5.5 kg
=7.96m/sec^2

Velocity at 10.5 secs is
v=a*t
v=7.96m/sec^2 *10.5 sec
=83.6 m/sec

Net Force on Instruments, see above
F=43.8 N

Velocity becomes downward
Vo=83.6 m/sec
Vf = 0
Vo-Vf=a*t
t=(Vo-Vf)/a
a=g=-9.8m/s^2
t=(83.6m/sec-0)/-9.8m/sec^2
=8.5 secs

Answer 2

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