[-/2.1 Points] DETAILS MY NOTES ASK YOUR TEACHER A spherical weather balloon is filled with hydrogen until its radius is 4.50 m. Its total mass including the instruments it carries is 24.0 kg. (a) Find the buoyant force acting on the balloon, assuming the density of air is 1.29 kg/m. KN (b) What is the net force acting on the balloon and its instruments after the balloon is released from the ground? KN (c) Why does the radius of the balloon tend to increase as it rises to higher altitude? Because the external pressur ---Select--- increasing altitude. Submit Answer decreases increases