A meter stick lies at the bottom of a 100cm long tank by its zero mark against the left edge. You look into a tank at 30 degree angle, by your line of sight gazing the upper left edge. (a) What mark do you see on the meter stick if the tank is empty? (b) What mark do you see on the meter if the tank is half full of water? (c) What mark do you see on the meter stick if the tank is totally full with water?