Determine the modification of a stem that provides storage.

Underground stems are plant components that have specialized stem tissues under the soil surface. This provides storage for food and nutrients of the plant. 

When the ball is rising up, it gains kinetic energy. when the ball reaches the very top, it will have all potential energy, until it falls back down and gains it kinetic energy. finally when you catch the ball or it falls back down, it would have gained its potential energy back.