Final answer:
When a ball is tossed up without air resistance, the potential energy is not the same as the kinetic energy.
Step-by-step explanation:
When a ball is tossed up without any air resistance, the potential energy is not the same as the kinetic energy. As the ball is initially tossed up, it gains potential energy due to its height above the ground. At this moment, the kinetic energy is zero because the ball is at rest.
As the ball falls back down, the potential energy decreases and the kinetic energy increases. When the ball reaches its highest point, the potential energy is at its maximum and the kinetic energy is temporarily zero. At any other point in the ball's trajectory, the potential energy and kinetic energy are unequal.