A large aquarium has portholes of thin transparent plastic with a radius of curvature of 1.90 m and their convex sides facing into the water. A shark hovers in front of a porthole, sizing up the dinner prospects outside the tank. Required:
a. If one of the shark's teeth is exactly 46.5 cm from the plastic, how far from the plastic does it appear to be to observers outside the tank?
b. Does the shark appear to be right side up or upside down?
c. If the tooth has an actual length of 5.00 cm, how long does it appear to the observers?

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?