A ball is thrown upward What can be said about the system?

Well, honey, when a ball is thrown upward, the system is experiencing an increase in potential energy and a decrease in kinetic energy. As the ball reaches its highest point, its potential energy is at its maximum and its kinetic energy is at its minimum. Once gravity takes over and brings that ball back down, the potential energy decreases while the kinetic energy increases. It's just physics doing its thing, darling.