[" 4) All of these "],[" 23.A ball is thrown vertically upward with a "],[" velocity "u" from the balloon descending with a "],[" constant velocity "v" .The ball will pass by the "],[" balloon after time "],[[" 1) "(u+v)/(2g)," 2) "(2u+v)/(g)," 3) "(2u+2v)/(g)," 4) "((u+v))/(g)]]