Answer:
4515.49484 N
4329.10484 N
Explanation:
r = Radius of balloon = 4.4 m
m = Mass of balloon with instruments = 19 kg
g = Acceleration due to gravity = 9.81 m/s²
Volume of balloon

The Buoyant force = Weight of the air displaced

The buoyant force acting on the balloon is 4515.49484 N
Net force on the balloon

The net force on the balloon is given by 4329.10484 N
As the balloon goes up the pressure outside reduces as the density of air decreases while the air pressure inside the balloon is high hence, the radius of the balloon tend to increase as it rises to higher altitude.
Answer:
the rate of change in volume with time is 280πr² cm³/min
Explanation:
Data provided in the question:
Radius of the sphere as 'r'
= 70 cm/min
Volume of the sphere, V =
Surface area of the sphere as 4πr²
Now,
Rate of change in volume with time,
=
=
Substituting the value of 
=
= 280πr² cm³/min
Hence, the rate of change in volume with time is 280πr² cm³/min
I believe the answer would be B) ...... sorry if i'm wrong
C. The Independent variable
It is the variable that you manipulate, while dependent is the response.