Which of the following is a problem with the estimated age of the universe? There are stars in our galaxy that appear to be over 15 billion years old.

The universe is shrinking, which makes it is impossible to tell how old it is.

There should be more supergiants if the universe is really about ten billion years old.

There are planets in other galaxies that are less than five billion years old.

Na food processing facility, a spherical container of inner radius r1 5 40 cm, outer radius r2 5 41 cm, and ther- mal conductivity k 5 1.5 w/m · k is used to store hot water and to keep it at 100°c at all times. to accomplish this, the outer surface of the container is wrapped with a 800-w electric strip heater and then insulated. the temperature of the inner surface of the container is observed to be nearly 120°c at all times. as- suming 10 percent of the heat generated in the heater is lost through the insulation, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the container, (b) obtain a relation for the variation of temperature in the container material by solving the differential equation, and (c) evaluate the outer surface tempera- ture of the container. also determine how much water at 100°c this tank can supply steadily if the cold water enters at 20°c.

How are positive ions different from neutral atoms

Which of the following statements correctly describes a transformer?