Scientists are studying a group of living cells under a microscope. They write down notes about the size, shape, and color of the cells as well as other traits. Which best describes this type of investigation?
A: comparative, because the scientists will be making observations in order to form a hypothesis
B: comparative, because the scientists are measuring dependent and independent variables
C: descriptive, because the scientists are using independent variables to test a hypothesis
D: descriptive, because the scientists are writing down observations but not making comparisons

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.

Time remainin52: 42the chart shows data for a moving object. which conclusion is best supported by the information inthe chart? time (s)velocity (m/s

Two point charges are on the y axis. a 3.90-µc charge is located at y = 1.25 cm, and a -2.4-µc charge is located at y = −1.80 cm. (a) find the total electric potential at the origin. v (b) find the total electric potential at the point whose coordinates are (1.50 cm, 0). v