Martin is conducting an experiment. His first test gives him a yield of 5.2 grams. His second test gives him a yield of 5.3 grams. His third test gives him a yield of 5.0 grams. The known yield of the substance is 5.1 grams of substance. Which of the following are true? a
His results are neither accurate nor precise.
b
His results are precise but not accurate.
c
His results are both accurate and precise.
d
His results are accurate but not precise.

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.

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

Compare the horizontal displacement of the two balls as they travel to the ground. what do you observe?