Large groups of sunspots can be relatively long-lived (a few months) and they remain essentially fixed at the same physical location on the photosphere throughout their lives. suppose a sunspot appears to move from the center to the edge (limb) of the sun's disk in 7 days. what is the approximate rotation period of the sun? (a rough estimate will suffice; don't worry about not being able to see the sunspot if it is exactly at the edge of the sun.) [p.275 q.14]

A2-m rigid tank initially contains saturated water vapor at 100 kpa. the tank is connected to a supply line through a valve. steam is flowing in the supply line at 600 kpa and 300 c. the valve is opened, and steam is allowed to enter the tank until the pressure in the tank reaches the line pressure, at which point the valve is closed. a thermometer placed in the tank indicates that the temperature at the final state is 200°c. determine (a) the mass of steam that has entered the tank (b) the amount of heat transfer.