The 100-cm-tall, 100-cm-wide tank is completely filled with water. As you stand beside the opposite wall, your eye is level with the top of the water.
(a) Can you see the side marks from the top of the tank (the 0 cm mark) going down, or from the bottom of the tank (the 100 cm mark) coming up?
(b) Which is the lowest or highest mark, depending on your answer to part (a), that you can see?
(c) As you rotate your gaze, but still with your line of sight just grazing the upper left edge of the tank, can you see the entire bottom of the tank? Explain.
