Q1. A 46 kg girl is standing on a 145 kg plank. The plank, initially at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.52 m/s relative to plank. What is her velocity relative to the ice surface?
Q2. An aquarium contains a 5-cm layer of water (n = 1.333) floating on top of carbon tetrachloride (n = 1.461). If an angle of incidence into water from the carbon tetrachloride is 20, what is the angle of refraction into the air?