Given that
Radius r = 3.40 m
Mass m = 11 kg
Density of air ? = 1.29 kg/m^3
(a)
Volume of the balloon V = (4/3) ? r^3
                                     Â
= (4/3) ?( 3.40 m)^3
                                     Â
=164.55 m^3
Buoyant force Fb = Weight of the air displaced
                           Â
= ? V g
                             =
(1.29 kg/m^3 ) (164.552 m^3)( 9.8 m/s2)
                           Â
= 2080.275 N
(b)
The net force acting on the balloon and its instruments after the
balloon is released from the ground
                   Â
F = Fb - W
                        =
Fb - mg
                        =
2080.275 N- (11 kg ) (9.8 m/s2 )
                        =
1972.475 N
